Lapis Lazuli Value
Accompanying value information:
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Lapis lazuli value is determined almost exclusively by color. A deep, intense, blue with violet tones would be at the apex. Fine grained, uniform specimens can attain a smooth, highly polished surface not seen in lower grades.
Calcite inclusions almost always lower the value, but pyrite inclusions enhance it in the minds of many collectors and jewelry lovers. Although enthusiasts may debate how much pyrite is ideal in lapis lazuli, most would agree that the less calcite, the better the stone. Calcite can be seen as streaks or patches within the darker blue or can predominate in the mix, giving the rock an overall lighter blue shade.
Polish quality and faceting artistry also affect value.