Sintered Cobalt Rich Blue Spinel

This has been produced (1954) as a lapis lazuli imitation. The material is sintered under heat and pressure from spinel powder + suitable coloring matter. Flecks of gold or gold-colored metal are included to imitate pyrite.

For detection, magnification is the best. Look at the granular structure and also check under Chelsea Color Filter. Under the Chelsea Color Filter the material appears red while natural lapis lazuli tend to appear dull red/brown. Also look for the cobalt spectrum.