Synthetic: Flux Melt
Identification Tools Required: Magnification, Chelsea filter, diffraction grating spectroscope.
How to Identify:
Primary Test: Magnification will be the primary test because the flux melt process leaves diagnostic inclusions that make the identification fairly easy……usually. We say usually because sometimes the inclusions can be confusing and secondary tests will be required. The two most important types of inclusions are veils and fingerprints.
The important part of the veil identification is to remember that natural emeralds will also have veil inclusions, but they form differently than flux melt veils. Flux melt veils will have a tendency to turn back in toward themselves, while natural veils will be longer and straighter due to crystal growth. The curved veils of flux melt emeralds can be seen in the images below. Again this is an indicator that can be used by those with experience in emerald evaluation. For those without experience this will only be a supporting test.
Fingerprint inclusions are another issue that can occur in natural emeralds, but the flux melt fingerprints will vary significantly from the naturals. The main factor in flux melt fingerprint inclusions is that they are full of flux, a residual from the flux melt formation process. The results in a fingerprint inclusion that is larger with the lines of the print larger and filled with flux, while natural fingerprint inclusions will be smaller and the lines will be grain lines rather than filled tubes.
For those experienced with emeralds the above types of inclusions can be diagnostic. For those not well experienced with the identification of emeralds then the following tests should be used as either primary or confirmation tests.
Secondary Tests: The Chelsea filter will be a very important tool due to the fact that synthetic flux melt emeralds will contain far more chromium used in the synthesis to give the stones the best possible green color. As a result of this the red reaction of the Chelsea filter will usually be very intense with the synthetic emeralds, far more than naturals.
Another result of the higher amount of chromium in the flux melt emerald is that the chromium lines in the spectroscope will be more intense and clear than is normally seen in naturals. The greater concentration of chromium in the flux melt emeralds will provide a text book reaction in the spectroscope. For those experienced with observing natural chromium based emeralds through a spectroscope the difference in the intensity of the Cr line can be a very strong indicator for a all synthetic emeralds.
Repair and Setting: As a true synthetic emerald normal care should be taken as with natural emerald. No heat on or near the stone. The one good issue is that these lab grown emeralds are not oiled or treated for color enhancement using processes that can be removed by ultrasonic cleaning. Care should still be taken when cleaning not to over heat the stone. However since the stones are not oiled this removes the concern of special care regarding that issue