Gemstone treatment
Sugar-Acid Treatment, Opal
Black or dark brown body color with enhanced play-of-color contrast. Dark material may concentrate in cracks or porous structure.
01
What to look for
Black or dark brown body color with enhanced play-of-color contrast. Dark material may concentrate in cracks or porous structure.
02
What it means
Sugar and acid create carbon inside porous opal to darken the body. It can imitate more valuable black opal.
03
Expert move
Look for uneven dark color in cracks and on edges. Treat low-priced black-looking opal with caution.