How To Appraise A Rough Gemstone
When appraising a rough gemstone generally, if it looks good chances are it is. High value gem grade stones are crisp, clear, transparent and a glass like colour of the typical colour that particular stone may come in.
If you can’t see through, or into the rough it may not be a good piece. However, don’t discard just yet as a closer inspection is always needed. Strong lights can see into a gem rough that maybe the eyes can’t. A murky piece with a few marks in it is more likely to be made into a cabochon (a dome) that can still be very attractive once set.
Being bright is good to, if the gem bounces back light at you or in all directions, chances are its a good one and of course, the bigger the gemstone the more valuable they are!
Here are a few terms we use in the gem industry:
Opaque: No light shines through the gem (not as valuable unless its high grade black opal)
Translucent: Some light can go into gem.
Transparent: A high proportion of the light can go through the gem (often more valuable)