Brown Sapphire Rough, Dark Pulled Sapphire Crystals

These are lab created Czochralski pulled brown and dark sapphire facet rough.  Brown and gray sapphires are uncommon. We suspect that this was a failed experiment. The zoning seems to indicate an attempt at color treatment but it's unclear.  

These are all czochralski grown, a more expensive and demanding growth method that produces crystals of high chemical purity and structural perfection which are suitable for technical applications.