GEMSTONE ENHANCEMENT

Gemstone enhancement simply makes gemstones look better. It can be good, but more often is not, especially when material of inferior grade is made to look like something it isn’t or when material of an inferior grade is made to look like the same material of a higher quality. Disclosure of treatments is controversial in the jewelry trade.

1. Amber is fossilized tree sap, often with insects trapped inside and has many treatments.

1. Clarified amber is heated while immersed in oil to near melting point, causing bubbles to escape but often causing flower-like inclusions due to discoid fractures.
2. Hiding fractures by oiling.
3. Heating to 120 degrees C lots of small pieces of amber, then compressing to a brick and recutting.

2. Oiling emeralds – oil conceals fractures and oiling usually not disclosed.

1. Mineral oil overtime is removed from a stone. Stones can be reoiled, but impurities (dust, dirt) get into the oil each time with an eventual unsightly build-up in the fractures.
2. Canadian balsam is a resin similar to amber, is soft and durable, and conceals fractures better.
3. Opal, tourmaline, and amber also oiled.
4. Best to use an oil with a refractive index same or similar to the refractive index of the gemstone being oiled, making it less visible.
5. Good stones don’t take oil because they don’t have surface fractures as inferior stones do.

3. Coatings done to aquamarines, beryls, and diamonds to add color. Detection possible on facet junctions and the girdle where the coating abrades off at these sharp edges.
4. Heat-treated beryl (aquamarine, emerald) -- to change color from blue and yellow to a stable green color. Maxixe beryl is a natural pink color heated to a dark blue that will fade and is not stable.
5. Dyed massive calcite to imitate coral or lapis lazuli can be detected with hydrochloric acid or lack of true coral structure.
6. Black coral put in a strong oxidizer will be bleached and look like golden beryl.
7. Heat-treated corundum is very common and done to improve color.
8. Diffusion treated corundum – where prefaceted stones are coated with chemical oxides that produce desired colors and are heated to temperatures close to corundum’s melting point. A thin, subsurface layer of color is produced but is detectable as color concentrations on the girdle and facet junctions.
9. Diffusion treated synthetic corundums – to imitate diffusion treated natural corundums that are more expensive.
10. Induced fingerprints inside synthetic corundums are manmade inclusions imitating natural inclusions.
11. Glass-filled fractures – usually in corundums.
12. Small piece of natural ruby epoxied into the fracture of a larger ruby.
13. Irradiated corundum – causes a better color, but usually not stable. Very controversial.
14. Coated colored diamonds – detection usually simple because coating is not as hard as a diamond and is easily scratched. Therefore, colored diamonds with scratches are suspicious, although harder coatings are starting to be used.
15. Cyclotron-treated colored diamonds – are easily detectable because colors produced are localized, usually on the facet junctions.

16. Laser drilled diamonds – where black or dark inclusions in the diamond are dissolved by lasers but are replaced by white inclusions and an entry hole.
17. Dyes

18. Opals have many treatments:

1. Oiling
2. Plastic impregnated.
3. Smoked
4. Sugar treatment and sulfuric acid

19. Pearls have many treatments:

1. Dyes often detectable around the drill hole.
2. Black or dark colored mother-of-pearl beads with a thin layer of nacre grown over it.
3. Make pearls or blister pearls from inside of shell.

20. Dyed agates or chalcedony is common, has many varieties and is an accepted form of treatment usually not disclosed. Almost all black onyx is dyed black chalcedony.
21. Heat treating amethyst and citrine – where amethyst is heated to produce citrine or ametrine, a bicolor stone that is part amethyst, part citrine.
22. Quartz is heated, where it quench crackles, and then dyed to look like ruby or emerald.
23. Irradiated spodumene – to change the color with the irradiation often being dangerous and not stable. Kunzite, a natural pinkish variety of spodumene, will fade in sunlight.
24. Pinking topaz – where brown to orange topaz is heated to a stable pink color
25. Blue topaz can be natural or treated if the color is light blue. All dark blue topazes are treated by irradiation and heating, a two-step procedure.
26. Tourmaline has many treatments:

1. Dyed
2. Oiled for fracture concealment
3. Irradiated to change color from pale pink to red
4. Cat’s-eye tourmaline – where cat’s-eye created by lots of parallel tubes in the stone that are sometimes sealed with epoxy.

27. Turquoise can be plastic treated or doublets created with a thin turquoise layer glued to a black backing material.
28. Blue zircon is all treated since no natural blue exists and is created by heating brown, red, or green zircon.
29. Cat’s-eye zircon can be natural, but always check for mineral coatings on the back for treated cat’s-eye zircons.
30. Tanzanite can be heated to create beautiful blue colors.

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