In 1981, ammolite became recognized by CIBJO, (the Colored Stones Commission.) It is the latest of only three new gemstones introduced in the last 50 years. It is also only one of three organic gemstones, (including amber & pearl.) It has been compared to opal and has a superficial similarity to the Austrian mineral lumachelle whose iridescence is also provided by the fossil ammonite carnites floridus.
... Ammonite shell is comprised primarily of aragonite, (the same mineral that makes up pearls,) with trace elements of aluminum, barium, chromium, copper, iron, magnesium, manganese, silicon, strontium, titanium and vanadium.
... Unlike most other gem, whose colors comes from light refraction, the iridescent color of ammolite comes from interference with the light that rebounds from stacked layers of thin platelets in the aragonite. Ordered thick stacks for red gems, less ordered thinner stacks for green and unordered, very thin stacks for blue ones.
Boulder opal earrings in 22k 18k gold with zircon and sapphire accents. Comfortable, striking and...
Pentagon shaped boulder opal with blue green fire. The boulder opal is wrapped in 22k...
Soft pastels in this boulder opal, really lovely. Fire of green, blue and purple in...