Introduction:
Original imagery as taken by AJS Gems.
This is part 1 of 3 in a series of a study of corundum specimens. This document entails a study using micrographs and various non-destructive study and examination with instrumentation available. This document details observations as noted, along with supporting imagery.
The first specimen examined was a purple sapphire disclosed as being heat treated in a manner that virtually all sapphires are treated in (with some rare exceptions). The specimen was also disclosed as originating from Madagascar.
Objectives:
The following objectives were defined in this study.
- Is the stone examined in fact natural or synthetic?
- Is there any evidence of additional of different thermal enhancements other than those disclosed at the time of sale?
- Is there any evidence to support the origin of this stone?
Background:
There is very little information that is conclusive as to purple sapphires that are published and readily available. What information that is available online collectively is conflicting or inconclusive as to properties of synthetics with respect to UV fluorescence, chemical composition, etc.
As with any synthetic corundum, strong fluorescence of certain colors denotes a synthetic. This particular specimen appears to glow pink to pinkish red under exposure to UV-A using a hand held UV lamp. Many sources cite this as being a tell tale sign of a synthetic. However, the GIA published an article in Gems and Gemology citing a moderate to strong fluorescence in purple sapphires from Pakistan. The material used in the study was said to be in the range of light purple to shades overlapping amethyst and plum colors. It also cites origins of like material to be from Tanzania, Ceylon, etc.
Based on that source, the test for UV fluorescence is inconclusive as to the stone being natural or synthetic, and it doesn’t conclude the origin to be Madagascar or anywhere else. So as such, we have another possibility of origin.
Much is published citing vanadium as being the coloring agent for purple sapphire, and other sources suggest this to be what is responsible for making some sapphires change colors. Other sources suggest the purple being the mixture of a sapphire and a ruby. In such a case, titanium with chromium would blend in the aluminum oxide matrix, and accept iron as a toning agent to produce a certain color. In either case, it would be a rare combination of elements to combine as such to produce this material. Regardless, many sources say that where rubies and sapphires are found, purple sapphires are found as well. This would imply (at least) that is possible for this stone to be from Madagascar since it is a known source for both rubies and sapphires.
