This following information is free. I am prepared to answer more complicated queries by E mail free of charge. I have 40 years of experience in all types of Jewellery manufacture, repair and Gemmology, and am a former Gemmology Diploma Tutor. Send Comments,E mails to    pmolieff@hotmail.com                                      some items for sale

                 Diamonds-click for larger picture    
                    
             5 Colours         5 cuts             The Regent    The Hope

                        More Pictures of Gemstones & Crystals
Citrine    Citrine Crystal    Aquamarine     Opal     Tanzanite ring      Tanzanite crystal
Sapphire in ring    Morganite crystal     Rhodolite Garnet   Strontium Titanate
                                    
Hallmarks
By English law, all items for sale must bear a hallmark. There are some exceptions to this. The following standards are available today in the UK
9ct, 14ct, 18ct, 22ct  (·375, ·585, ·750, ·916 )  These figure refer to % purity of Gold. 
(i.e.  9ct is 37·5% Gold, or 9/24ths  -  18ct is 75.0% Gold or 18/24ths )
Britannia Silver, Sterling Silver  (·958, ·925 ) i.e. 95.8% and 92.5%
The hallmark thus bears a figure corresponding to carat of the gold, or percentage of Silver in the alloy.
Silver items carry a Lion mark for Sterling, and a Britannia figure for the Britannia Standard.
The hallmark also carries a mark corresponding to the Assay office that tested and applied the hallmark. These are, London-a leopard’s head, Birmingham-an anchor, Sheffield-a rose, Edinburgh- a castle.
A mark for the date is applied in a shield, the design of the font and shape of the shield represent dates in the past. A serious user of hallmarks will buy a specialist reference book which dates back many centuries. Bradbury's Book of Hallmarks being such a publication.
The last mark is for the maker of the piece.
In addition to the standard hall marks, other marks have in the past  been applied, these include- duty marks, commemorative marks and marks of former assay offices.
To study hallmarks more clearly, a lens is used, either 2-3X or 10X. The 10X lens is the standard for examining gemstones, jewellery etc.

Gold, Silver tests & 10x lens
The popular test for Gold bearing alloys is the use of nitric acid. This is the easiest and least complicated test. If a small drop of nitric acid is applied to the surface of a gold bearing alloy, the following will be noticed-
Pure Gold and 22ct -no apparent effect noticed.
!8 ct Gold –no apparent effect.
9ct Gold – very, very, slight effervescence noted and brown discoloration. (it is the other metals in the alloy that  react with the acid).
14, 15ct Gold – very slight brown discoloration (these discolorations also apply to white golds)
Non Gold items, brass etc –effervescence and green discoloration, smell of nitrogen dioxide.
However, the item in question may be gold plated. It is for this reason that a small  area of the surface is carefully filed to reveal the  underlying metal. This should be done in an inconspicuous area and should not damage the piece.
Silver
Pure Silver –slight white discoloration
Sterling Silver –very slight grey discoloration.
Some Oriental Silver (approx 60-70%) –dark grey, sometimes slightly green discoloration, odour. (Silver coins pre 1920 will show this)
Other materials with no Silver content –green or dark discoloration, effervescence and stronger odour, rapid action.
Platinum –no effect whatsoever.
These effects can also be observed using a lens.

Valuations
This is a confusing area; an object is worth what you can get for it.
Insurance or replacement valuations are inflated so that in theory you can go out and buy another similar piece to replace one lost. Imagine if you had a rare handmade item, you could commission another to be made, so sufficient funds have to be available for this option. You may have to search high and low to find a replacement piece, and have to pay the asking price. The insurance value thus reflects these options.
Probate value is what you can raise quickly for an item, often at a public auction. Do not confuse with replacement values.
Retail value applies to the price asked for jewellery on the high street.
Should you try to sell your item to retail or manufacturing jewellers, you will only get a proportion of the retail value. Retailers can often buy more than they can sell, so invariably some items will be scrapped i.e. the gold be melted and re-used or sold to a bullion dealer. Diamonds and some precious stones can be re-used, or reset. Accordingly, the jeweller will make an offer based on this premise.
An alternative is to leave the item with your jeweller and let him try to sell it for you. I have sold many items in this manner, settling for a lower profit, thus giving the customer a much higher value.
Auctions
If you sell your item at an auction, this is something of a lottery. If sold in a room full of dealers, you will get  a lower price, possibly much lower than you anticipated. If however there are many private buyers or collectors present, you usually will get a higher price.
This however depends on certain factors, mainly supply and demand and unfortunately there are some people with more money than sense who may raise the bidding to an inflated level. Your price raised in thus dependant on the audience, time of year, supply & demand and the state of the market.

Manufacturing Techniques
Casting
To cast an object requires some sort of mould, these can be quite crude or very complicated. A simple mould can be made with cuttle fish bone. If an item be  pressed into 2 pieces of cuttle fish bone, a rough mould is formed, the gold or silver is then melted and poured into the mould and an approximate copy of the item is formed. This however may need much filling, drilling, and shaping with handtools to create the desired effect.
An older form was wax casting, from beeswax, an object was sculptured. The finished shape was then covered with layers of clay and then baked in a fire. The wax melted, ran out of the mould forming a cavity in the exact shape of the sculpture. The molten metal was then poured into the mould. Bronzes are made using this method.
This method has been sophisticated today but the basic principle remains. The wax impressions are produced in volume from rubber pliable moulds and cast using centrifugal force. Anything from silver charms to complex rings are made today by this method.
Fabrication
Construction using separate sections, soldered together, a hand made ring for example.
Shaping
Can be repoussé work, beaten out carefully from the reverse of the article. Items are also shaped on mandrills, small anvils or silversmithing stakes. Some soldering is usually involved.
Carving
Delicate setting patterns and some ring shanks are carved from larger blanks with the use of engraving tools.

Ring sizing
There are very few rings that cannot be resized. These include some completely patterned wedding rings, full eternity rings and rings containing stones or enamel that make sizing impossible. The heat during soldering would damage such materials. Opals, Pearls, Turquoise, Emeralds make life difficult. Sometimes, by the way that a stone is set, removal for sizing is impossible. Diamonds, Sapphire and Rubies will take a modicum of heat without damage, but there is always an element of risk. Such risks should always be explained to you in advance. A good professional jeweller will do this, others may not.
Basically, a ring is made smaller by removing a piece of material, and rejoining the shank. The ring must then be made round again, taking care not to disturb any settings on the shank. When completed, you should not be able to see any evidence of the join or work. Similar colour solders are used for this purpose, 18ct solder used for 18ct gold etc.
Rings are made larger by the addition of a piece of similar material, in this case there are two solder joints to disguise, and if done properly, the work should be invisible. Again care should be taken with stone set rings. Some patterned rings can be enlarged in this manner and the pattern copied on to the gold.
A plain wedding ring can be made smaller by a shrinking process; and also made bigger by a stretching process. This is only applicable to seamless rings and any enlargement is limited.

Replacing shanks
After many years of wear, shanks often become worn at the back due to friction from a wedding ring. There can also be wear to the setting. The worn section can be cut away and a new shank fitted in it's place. White gold or Platinum may also be grafted on to the setting part of the ring and the metal carefully refilled to the original shape. Should the ring contain stones that could be damaged by the heat, they are removed during soldering. If performed correctly this repair should be good for another twenty years or so

Replacing any worn part
Virtually any worn part or section can be replaced or repaired on a piece of jewellery. Factors influencing this are-if the piece has gemstones or enamel, or the overall condition of the piece and viability of the repair. Pieces are often found with lead solder repairs on them. This is a quick and very amateurish way of effecting a temporary repair. This technique usually damages the item beyond help, as gold forms an amalgam with lead and ceases to behave as gold.

Ring making, remodelling
When a ring gets past repair, remaking is the only option, the original style can be reproduced or re-designed in a different manner.
Another popular procedure is remodelling. Often two of more wedding rings are combined by re-melting, re-hallmarking and remaking. This is not a difficult operation and retains the sentimentality of the piece.

Setting
Basically there are 3 forms of securing a stone.
Cabochon
The simplest form of setting, the stone is secured by a band of metal which is then rubbed or hammered over the stone. This mainly used for cabochon cut stones (oval or rounded form with no facets, but a flat back to the stone.)
Raised claw settings or Pavé
The stone sits in a hole carefully cut by the jeweller, and gold claws are raised by the use of gravers. These press on the stone and hold it in place. Decoration is also added by the setter. This used for smaller stones, often formed in a group to give an overall shape of effect. When used with larger diamonds this gives an effect of illusion and is known as Illusion Set.
Claw set
Claws are used almost like fingers gripping the stone. The stone sits in a bearing area of the claw. This a weakened section of the claw made by the jeweller where the claw will bend above this and be rubbed over the stone. The claw is carefully shaped before setting and the stone must sit firmly and geometrically in the setting before the final act of setting. This method is used for all types of cut gemstones and when set; claws should be smooth and as inconspicuous as possible. Platinum was favoured for important diamonds due to it's resistance to wear and its ease in working. 
Diamonds and Precious stones
Diamonds   
Prized since ancient times, the name exists from adamus (that that cannot be broken) this was a way of testing diamonds in ancient times. If the stone withstood a heavy blow from a hammer it was a diamond. Many stone must have been ruined in this manner. A Diamond will cleave in certain directions more easily. The Cullinan, a massive 3,106 carat stone was cleaved into 3 pieces by Asscher & Co, Amsterdam. The resulting cut stones form the principal stones of the Crown Jewels, along with the Koh I Nur. The Koh I Nur, from the Golconda mines in India, was the largest most important Diamond known up to the discovery of the Cullinan in South Africa.
Diamonds are cut in all forms, the modern brilliant being the most popular. Older stones are often found with a thicker form of brilliant cut, sometimes not as effective as modern stones. The primitive form is the rose cut, the stones having a flat base.
It is the importance of proportion that makes the diamond so effective. The angles should be precise thus enabling the reflective and refractive properties to work at their best. Ideally white light enters the front of the stone, is reflected around the inside and emerges again from the top facets having suffered a dispersion effect during the journey. Some of the white light now becomes the spectrum colours giving the diamond is glittering effect.
In the 1920s, Tolkowsky, a resourseful cutter and mathematician, formulated the modern brilliant cut. Much shallower, with a wider table facet, many people were reluctant at first to adopt his proportions. Most diamonds today are cut quite close to his proportions and the family still trade as diamond cutters and merchants.
Diamonds are also cut in fancy forms, often dictated by the rough diamond shape for maximum size and effect. The Cullinan Diamond yielded the following important stones.
a pendeloque (tear drop shape)   weighing 530.2 carats
a square brilliant weighing 317.4 carats
another pendeloque weighing 94.5 carats
another square brilliant weighing 63.7 carats
There were also 101 more assorted stones cut from the rest, this represents a weight loss in cutting of 65.75% (in powder, chips etc)
Many of the stones were incorporated into the Crown Jewels and are seen regularly at state occasions.
There are many famous diamonds in history, too many to describe here, but two do deserve a mention.
The Hope Diamond
The French traveller Tavernier bought a blue diamond that had been found in the Golconda mines in 1642. This is a very rare colour for a diamond. He sold the diamond to Louis XIV in 1668, it then weighed 67 carats. In 1792 it was stolen during the French Revolution.
 In 1830 a blue stone appeared in London and was bought by the London banker and collector Henry Thomas Hope for £18,000. It had been recut at some time and now weighed 44.4 carats. Two other small blue stones were known at the time and the combined weight with a loss for recutting, would account for the original blue stone. Last century it was bought by Harry Winston and presented to the Smithsonian Institute in Washington DC. It is a cushion shaped irregular brilliant and is unique, the only important blue diamond known. photo
The Regent or Pitt
Discovered near Golconda in 1701, and weighing 410 carats in the rough, it was eventually bought by William Pitt , governor of Madras for £20.400. On his return to England he had it cut into a cushion brilliant weighing 140.5 carats (measuring 30mm by 25 mm and 17mm in depth). In 1717 he sold the stone to the Duc d'Orleans, Regent of France for £135,000. It was stolen during the revolution in 1792 from the Garde Meuble but eventually returned by the thieves. It is exhibited in the Louvre today.  photo
Ruby
Now commanding high prices and  used mainly along with Diamonds. “Pigeons Blood” describes the finest colour, but a whole range of colours is possible from deep red to purple. Ruby cat's eyes are seen, these are always cut en Cabochon with the star effect on the top of the stone.
Sapphire
The same family as Ruby but coloured by different impurities. Purple through to very dark blue, almost black. Ceylon Sapphires having the colour cornflower blue are amongst the finest examples. Also displays asterism or cat's  eye effect. 
Tanzanite
African stone which can resemble Sapphire.
Emerald & Aquamarine
The same family along with Morganite, a pink variety. Finest stones are  from Colombia and very expensive, and much simulated. Needs the use of microscope & spectroscope to detect imitations. Often cut in step form, rarely brilliant cut. Emeralds need care in wearing, they chip and break very easily.
Good Aquamarine is more green than blue. Blue varieties are of lesser value. Pink Morganite is a rarity.
Topaz
Distributed widely, Topaz comes in yellow, brown, blue and pink varieties. The finest stones come from South America and can command high prices. The golden and yellow varieties are rarely seen today, only in individual pieces. Most pink Topazes have been coloured artificially. Light blue variety is inexpensive.
Garnet
Often thought as a cheaper red stone, but good pyropes mainly from eastern Europe exist. The violet varieties of Almandine and Rhodolite can be striking. Rarer varieties exist; demantiod (green)  hessonite (orange red) and uvarovite (green) exist.
Opal
Popular stone, but very delicate and good examples are expensive. Harlequin is the most prized and a rare orange variety also exists as Mexican Fire Opal.
Pearl
Good examples of real Pearl are now beyond the reach of all but the very rich. To find and match for colour and size sufficient Pearls to make a necklet is a costly business. Specialist market exists for Pearl dealers.
Cultured Pearls however are widely used, for necklets and for Jewellery. A bead made from shell material is inserted into an oyster, the insertion then irritates the oyster. The intrusion is then covered by nacre, a hard enamel type covering, by the oyster. The oysters are harvested when sufficient nacre has formed on the bead. Quality & price varies enormously.
Pearls advertised in Majorca are a good quality synthetic imitation.
All Pearls must be worn with care and can need restringing after long use.  
Jade
Much prized in the orient, again a specialist market exists for good quality Jade. Often carved into figures or set in necklaces and rings.  Best qualities are bright grass green. Often imitated with many green minerals available to do this.
Ornamental Minerals
There are literally hundreds of varieties of minerals used in ornamental items and jewellery. Too many to list here. But popular types are-agates, quartz, malachite, feldspars, fluorspar, moonstone, jet, and ivory, shell, coral(organic)

Intaglios & Cameos, older cut stones
A cameo is a figure or illustration cut in relief, with the figure raised above the background. Shells are used for this because of the two colours that are present giving a contrasting effect. Many modern cameos are cut from shell with differing qualities of skill. This material is easy to work with due to its softness. Older cameos may be cut from much harder material such as quartz (agates and chalcedony) This is a specialist field and rare items command thousands of pounds, especially if the scene portrayed is of significance.
Intaglios are the opposite of cameos, with the figure cut into the stone. Often used as seal stones, these were invariably made from a harder material.
Other materials are extensively carved including Ivory, Jade, Jet, Mother of Pearl, Coral, Malachite.
Imitations & Fakes
Diamonds have been imitated since the introduction of paste. This is a soft lead glass fashioned into shapes and the back facets are silvered to produce a mirror effect. These also are known as diamante or rhinestones. French paste is a more refined variety with foil added to the back facets. These are usually set with the back of the stone covered and can at first glance, to less experienced jewellers, resemble diamonds to the untrained eye. Such stones are usually set in brooches and pendants. White Zircons have been passed as Diamonds, sometimes with coloured ink painted on to the back facets.
In the 1960s the first real diamond simulant appeared, Strontium Titanate or Fabulite. This soft stone however was too effective, with much more dispersion than diamond. Dispersion is the conversion of white incident light to the spectrum colours. His however did not stop the stone from being sold to many unwary buyers as diamond.
The next significant simulant was Cubic Zirconium. This was very effective and if the stones were mounted exactly as a diamond would be, it is difficult to detect for the untrained eye. Many jewellers bought these as diamonds, they are the correct colour, have sufficient hardness for wearing for a short period, but have no inclusions or flaws within the stones. A machine is available to tell the difference between diamonds, but these can be unreliable. These have now replaced white spinels as the stone for dress rings & pendants.
A mineral called Moissanite, after the Frenchman who detected it in a meteorite at the end of the 19th century has been synthesized in recent years. It is a crystallised form of Silicon Carbide and has been sucessfully cut as a gemstone. Available in differing colour shades, it is harder than Ruby, but much softer than Diamond and the dispersion is greater than that of Diamond. The rest of it's physical properties are similar to diamond.
However, I firmly believe that only Cubic Zirconium should give an experienced jeweller cause to  look more closely at a suspect stone.
Ask an art expert how he knows  a genuine Manet, he will say I just know from experience.
It`s the same for a good jeweller, doctor, mechanic or any good expert in their field.
True Casefile
A young jeweller once asked me if I was interested in buying some diamonds, I said I was always interested. I then proceded to look through about twenty stone of varying quality, similar color, priced at £80 -£120. I picked out what I wanted and told the jeweller I had had found one CZ amongst them. He was slightly embarrassed but thanked me.
Very easy for some apprentice to look through them quickly, request another look later, now with a CZ  carefully placed in his lap tray. He could easily drop a diamond into the tray and replace it with the CZ, dead easy!

Ruby
Rubies have been imitated since the 19^th century, the normal synthetic Ruby is not difficult to detect.  The colour is false and the stone is too good to be true. Synthetic corundum (Ruby) is made in a variety of colours resembling Sapphire, Aquamarine, Alexandrite and Topaz. There are however some modern day synthetics that are only detectable by an experienced gemmologist, by the use of laboratory equipment. There are however today, stones on the market that are not natural. These are very effective stones and some very sophisticated laboratory procedures are needed to verify or disclaim the stones as naturally occurring.
Sapphires
Not simulated to the same degree as Ruby, most synthetics tend to be rather obvious.
Emeralds
Emeralds were first simulated with doublets; these have a base of green glass and top of real stone often garnet. The green colour of the base gives an overall green colour to the stone. Careful examination with a 10x lens will reveal the joining of the 2 pieces. These were quite effective.
For 40 years or so Emeralds have been synthesised effectively in the laboratory. Gilson Emeralds being the most known type. These have the same properties as real stones but it is only by microscopic examination that the synthetic is detected. These have become even more refined and the services of an experienced gemmologist should be sought.

Many stones are synthesised today, these are mostly semi precious varieties. It is often easier and cheaper to produce them in this was than to mine them. These include Garnets, Cats eyes, and various coloured Spinels.
Diamonds- Word of Warning
Today there some very sophisticated methods of improving the colour and clarity of diamonds, various forms of electomagnetic radiation are used to improve or change the colour of diamonds.
Tiny beams of laser light are used to drill into diamonds and vaporise inclusions within the stone, thus improving the clarity of the stone. Unfortunately, most small laboratories don't have sufficient resources to equip for suitable diagnostic equipment. There are only a few institutions that can offer a professional verification service, one such laboratory being The Gübelin Laboratory in Schwitzerland.     http://www.gubelinlab.com
The colour of Sapphires and Rubies also have been altered in this manner.

Cleaning
It is relatively easy to clean most Jewellery, however, this may have the effect of loosening set stones, possibly only held in by dirt & grease deposits. So this must be done with care. A solution of washing up liquid and Ammonia will improve most gem set jewellery, if used carefully with a toothbrush or similar. Acetone (nail polish remover) will remove laquer  deposits and soaking in washing soda solution some others. Jewellers have often to resort to burning extremely stubborn deposits and use ultrasonic cleaners to achieve professional results. Do not resort to bleach, this can discolour some alloys. Do not rapidly heat or cool stones in water, this can crack them.
Avoid cleaning the following stones for fear of discoloration, breakage and fading the colour-
                                                 Opals, Turquoise, Coral, some Pearls, and Emeralds
Metal
The black tarnish on Silver can be removed with Silver Dip or photographers “hypo” crystals (sodium thiosulphate) in solution.
The main abrasive for polishing Silver by hand is chalk and water paste. Applied as you would with car wax. However, this form of regular cleaning also removes metal and eventually shows signs of wear especially on corners.
Anything that brightens brass will clean Gold, jewellers use “Jewellers Rouge” an iron oxide applied with a motor driven buffing mop.
Most ornamental jewellery will benefit from a light cleaning and drying with warm soap & water.

The Author
Peter M Olieff FGA(Dist)   Gemmologist and Manufacturing Jeweller of Doncaster, Yorkshire.
Son of a Jeweller.
Fellow of the Gemmological Association, Qualified with Distinction 1971,
Only 5 Distinctions awarded in 1971, ranking him in top 5, Internationally that year, at 22 years of age.
Invited to be Diploma Tutor (Sheffield Facility)

Any comments welcomed to      pmolieff@hotmail.com