Assignment 6 - Treatments Flashcards
Why are some gems treated?
Gems are treated for a number of reasons. Treatments can:
- Deepen, change, or remove color
- Improve clarity
- Create or accentuate phenomena and desirable inclusions
- Improve luster
How does treatment affect value?
- Treatments can make gemstones more appealing and dramatically increase their value.
- But the absence of treatment makes many stones more valuable than treated stones of similar apparent quality.
Why is treatment disclosure important?
Because it affects the value and in some cases the durability.
Any human-controlled process, beyond cutting and polishing, that improves the appearance,
durability, or value of a gem.
Treatment
What are the most common treatments?
- Heat Treatment
- Lattice Diffusion
- Glass Filling
- Irradiation
- Bleaching
- Dyeing
What stones are commonly heat-treated?
Commonly heat-treated gems include corundum, tanzanite, zircon, topaz, aquamarine, and amber.
What stones are commonly irradiated?
Commonly irradiated gems include topaz, tourmaline, and cultured pearl.
What gems are commonly bleached?
Bleaching is a fairly common pearl treatment.
Jadeite is often treated with a combination of bleaching and impregnation.
What stones are commonly dyed?
Commonly dyed gems include cultured
pearl, lapis lazuli, chalcedony, and coral.
How durable are some gem treatments?
Some treatments like heat-treatments are permanent, other are not.
Irradiated color is not always stable, and
exposure to heat or light can destroy it.
Exposing a gem to rising temperatures for the purpose of changing its appearance.
Heat treatment
An oxygen-rich environment that surrounds a gem during heat treatment, causing certain color-causing trace elements to lose electrons.
Oxidizing environment
A compound that can dissolve another compound at a lower temperature than its own melting point.
Flux
Heat treatment in the
presence of a flux that results in the
sealing of a fracture or cavity.
Flux healing
A treatment in which a gem is exposed to high
temperatures and chemicals to allow penetration of color-causing elements.
Lattice diffusion
How can you treat dark blue sapphire?
A combination of beryllium diffusion
and heat treatment can improve color in
some dark blue sapphires and make
them more marketable.
How deep does Lattice Diffusion penetrate a stone?
Lattice diffusion with heavier elements
like titanium and chromium produces a
shallow layer of color that might be
removed by minor repolishing.
The color resulting from lattice diffusion
with beryllium can penetrate the entire
stone.
A clear, viscous substance that’s
used to fill fractures in gemstones.
Resin
A liquid filling material
that’s very durable when it dries.
Polymer
A chemical that treaters
mix with some resins to cause them
to solidify.
Hardener
What is the most common treatment of emeralds?
Today, almost all emeralds on the market
are subjected to clarity enhancement.
Fracture filling is the most common
form of clarity enhancement.
Treatment that improves the apparent clarity of a gem with a colorless or near-colorless filler.
Clarity enhancement
Use of a colorless to near-colorless filler to conceal fractures and improve the apparent clarity of a gem.
Fracture (fissure) filling, as clarity enhancement
A treatment that adds color or affects color by deepening it, making it more even, or changing it.
Dyeing
