These are lab created Czochralski pulled yellow sapphire facet rough. The pieces are labelled with their letters and weights and can be purchased individually.
This is a gorgeous yellow sapphire, likely grown for watch cases. These have a very snappy yellow that cuts to an almost canary color.
These stones were produced by Czochralski pulling, which is a more expensive method which results in crystals with the extreme chemical purity and structural perfection needed for mechanical and scientific applications.
Note that K is very flat--it would be great for a fantasy cut or hybrid carving!
