Artificial products

Disclosure: in gemology this is the revealing of the true nature of gem material and in particular if it is natural, synthetic or has been treated.

Artificial: partially or entirely (eg: window glass or plastic) manufactured, with no natural counterpart.

Synthetic

Material with identical properties as the natural occurring material.

1800s first report of syn. gems. Now many minerals can be recreated to produce syn. stones eg: corundum (ruby and sapphire), beryl (emerald), quartz and diamonds.

Diamonds have simple chemical formula of carbon atoms (C). Atoms are arranged in a specific symmetrical way (crystalline structure). Natural diamonds take a long time to be created within the earth while syn. diamonds with the same properties and visually identical, take a short time in a lab (days or weeks). Need instruments to distinguish between them.

Nomenclature

Choosing of object names. Important in science / gemm'y / the trade. Gemmologists need to be up-to-date on correct trade and marketing terms. Helps to clearly communicate and helps consumers to make informed purchasing decisions / consumer confidence. Syn. is sometimes seen as a negative so often other terms are used eg: lab grown or lab created.

The World Jewellery Confederation (CIBJO) does not endorse the term 'cultured' as this is applied to biogenic gem material like pearls. Debate as to how to advertise syn. diamonds - 'cultured' or 'laboratory grown'. The latter is recommended.

CIBJO has 'blue books' grading standards and nomenclature for gemstones. It is revised.

Correct used of gem language can be in conflict with stricter scientific terminology and commercial vocab - as may be seen as ambiguous or incorrect. Eg: emerald is defined as a green variety of beryl. Red variety is called bixbite but sometimes referred to as 'red emerald' due to its rarity. This name is a misnomer and disapproved of by gemm'l commission due to the allusion to it as a type of emerald when it isn't.

Composite stones

Can bond two segments of material or different materials. Then cut and polish to create a whole stone = composite. Two segments = 'doublet' and three segments = 'triplet'. Others are agglomerates or mosaic-looking materials composed of many small fragments bonded together.

May be done to improve colour and appearance, add weight, increase durability or imitate other gemstones.

Garnet Topped Doublet (GTD): Oldest known doublet. Not as popular now but is still around. Hard to spot. Is a slice of garnet fused to glass. Junction line often not parallel to the top of the stone and hard to see. Turn the stone upside down on a white background, shone a light on the stone. A red shadow/ring will appear. This may be masked by other reddish coloured stones. Glass bottom of the stone may contain round gass bubbles - another clue. Good practice is to think 'doublet' when viewing gemstones.

Opal triplet: common composite stone. This slice of iridescent and colourful precious opal is glued onto a black material with a colourless, transparent, protective domed cap. Can detect using a loupe. There is also an unnatural look to the dome and may see the junction of layers if observing from the sides.

Artificial & Fakes

Other art. products may be crystalline in their internal arrangement but don't have naturally occurring counterpart in large sizes, may just occur in small amounts.

Most famous is the cubic zirconia (CZ):

• reported to be found in nature as minute microscopic grains inside the mineral zircon (not named at the time) and was created in a Russian lab decades ago.
• man-made, transparent, hard material suitable for use a a gem.
• best known for the colourless form and for its use as a diamond alternative, although exists in many colours, used esp. in low-cost jewellery.
• like diamond it has high dispersion or 'fire'. Diamond has many simulants therefore gemmologists need to look for clues to ID.
• colourless CZ looks similar but by using a 10x loupe and good lighting can see rounded facet edges, chips, bruises and grinding marks. Need the knowledge and experience for ID.

Fakes: includes synthetics and other imitation gems. Many kinds of fakes used for gems found to be counterfeit, forgery or imitation. Loosely - only imitations are called 'fakes' by gemmologists but the concept doesn't really exist as gem'ts ID materials, the circumstances of their use are not the gem'ts to define. Eg: gem'ts won't say 'fake' just 'red glass'.

Use the term 'imitation' or 'simulants'- can be natural or artificial that are used to imitate the effect, colour and appearance of gem materials, without having the same chemical & physical properties. Eg: Fine ruby has lookalikes - red spinal (red gemstone), red-coloured paste (artificial glass) and synthetic.

Glass

Commonly used in jewellery for 3000 years in its own right or as imitation of gems. Has internal bubbles and swirls may be present (some inclusion in natural gems look like gas bubbles). Glass never shows different colours with a dichroscope ie: it is not pleochroic.

'Paste' (glass used for imitation gems) is quite soft with Mohs' 5 to 5.5 so it is easily scratched or has worn facet edges. This is easily seen with a 10x loupe.