Viewed from the back, the curved colour banding clearly visible in this

flame fusion synthetic star sapphire.

The same stone viewed from the front, with the curved colour banding more difficult to see.

This is the rear view of a flame fusion synthetic ruby, which has been heated

 and then quenched in liquid to produce inclusions which mimic fingerprint and

 feather inclusions found in natural rubies.

This shot through table clearly shows the web-like appearance of the liquid

inclusions in this quench-cracked flame fusion synthetic ruby.

Another shot through table showing the liquid inclusions in this quench-cracked

 flame fusion synthetic ruby. Inclusions similar to these are common in

 quench-cracked flame fusion synthetic rubies.

Curved striae clearly visible in this flame fusion synthetic ruby.

Curved colour banding clearly visible in this flame fusion synthetic star sapphire.

Gas bubbles like those above, are another diagnostic inclusion in

 flame fusion synthetic sapphires and rubies.