Treatment: Diffusion on synthetic ruby
Identification Tools Required: Magnification.
How to Identify:
Primary Test: As with any diffused stone the process leaves a totally unnatural feature somewhere in or on the stone if you know where to look. With the diffused start rubies this feature is in the star itself. The star is first, too perfect. Natural star rubies of this quality are normally tens of thousands of dollars per carat, and very rare. So when a star ruby of this perfection is offered for a few dollars per carat that should be a very serious indicator. But when the sales price is not known the perfection of the stone alone should be a very strong indicator. The star will appear to be on the surface rather than inside the stone, which is indeed the case since the star is being generated by light interaction with the surface diffusion material. Also, in dark field the ruby structure will not be of the shape or orientation to produce a star since star spires will follow perpendicular to the crystal faces in natural star stones. When viewed with back lighting even star rubies using natural ruby crystals will normally show a ruby crystal whose orientation to the actual cut gemstone could not produce a star at all. This all adds up to the fact that the diffused star ruby is an easy identification if some time and proper magnification is applied to the effort.
Many of these stones are created from flame fusion synthetic ruby with a surface diffusion to create the star. As seen below, the curved striations of the flame fusion process is normally easy to identify under magnification.
Secondary Tests: None needed
Repair and Setting: The star is caused by surface diffusion which might be damaged during any heat from repairs or cleaning. Strongly recommend to unset for any repairs. No strong cleaning solutions and no high heat in an ultrasonic.