(1) Which gems can be synthesized? - Almost all gems can be synthesized!
(2) What is a synthetic
A synthetic is a man-made material, which has the same composition and crystal structure as the natural material.
(3) What are the general ways in which gems can be synthesized ?
: From melts, from solutions, ceramic and other techniques, and at high temperature and pressure
FROM MELT:
Melt same composition material
- melting methods differ
Not required for students of EPS 2
-stars formed by adding rutile powder and cooling slowly.
-often used to make rod-shaped single crystals
-esp. for ruby, sapphire, alexandrite, GGG, YAG
-lower a seed crystal into the melt, rotating the seed crystal
pull the seed out of the melt slowly, rotating
-final crystal resembles shape of crucible
-Developed in the 1950s for production of high-purity silicon
but is also used to grow gems
An infra red heat source moves down rod - ultimately giving single crystals
used for gems that have exceptionally high melting points or very
reactive
- for example, to synthesize CZ (cubic zirconia), with a melting point of
~ 2750 degrees C.
Chatham is one of several manufacturers of synthetic gems.
Crystals precipitate from a saturated solution -use high temperature (and pressure) to grow more perfect gems
Details not required for students of EPS 2
- It is especially useful for synthesis of quartz, emerald, and some unusual beryls
-water + seed crystals into autoclave, at hundreds of degrees C. - higher temperatures around the feed material - dissolution, xalize in cooler areas
Growth of ruby, sapphires, emerald, alexandrite
"Flux" is a substance that when molten will dissolve a material with a very high melting point. Flux growth is useful for synthesis of compounds with high melting points Flux is used as a molten solvent to sp eed crystallization up at lower pressures and temperatures
Flux (e.g., LiO, MoO, PbF2) mixed with powder in a crucible (e.g., Pt, Ir, Au-lined crucible) The contents are melted and cooled very slowly - crystals of high-melting compound form
pour off the still molten flux
Note: sometimes seed crystals are used)
CERAMIC TECHNIQUES:
DIAMOND SYNTHESIS:
This is not required information for students of EPS2.
Fraudulent claims:
The first real synthesis of diamonds occured in 1955: the GE Corporationused high P, T synthesis techniques.
METHOD: