a lustrous opal

Within this jewel, you can see a fire dancing as if it was living. Although the fire is coloured blue from the gem, it is obvious it is the light in the room, trapped within the opal's crystal.

It is a lustrous opal.
It weighs a couple of ounces.

You identify a lustrous opal.
It weighs two ounces, and it is worth about seven lauren and ten celeb.
Its keywords are opal, lustrous, jewel, and gem.