What do these words mean? I have confused them on many occasions. Let's sort it out.
According to Wiki adularescence is "As an optical phenomenon, adularescence exists only in the presence of light; it is a product of the interaction between light and the internal microstructures of the mineral and not a property of the mineral itself."
The Shiller Effect is what the rolling flow of color in a stone is called. You can think of it as the same as adularescence only easier to say and remember.
Moonstone has pure adularescence, that is, it has a milky to blue sheen of color on the face when the light is right.
|Rainbow Moonstone Adularescence or Shiller|
Other stones have shiller, too. When impurities or inclusions are present, the light is scattered differently. That is why you see different colors in other flashy stones.
When the shiller exists as a single line in the stone, it is said to be chatoyant, or exhibiting a cat's eye as in chrysoberyl and, rarely, jade.
|Russian Cat's Eye Jade with Chatoyancy or a Chatoyant Effect.|
Labradorescence is the type of adularescence that one sees in labradorite and spectrolite, for example. Those stones have a strong and colorful shiller effect.
|Spectrolite with Labradorescence or a Labradorescent Effect|
Opalescence is the type of beautiful shiller that one sees in opal.
|Australian Opal with Opalescence or an Opalescent Effect|
Aventurescence is another type of shiller which is found in adventurine, muscovite and fuschite. These stones have tiny inclusions which the light plays on to produce twinkles of light.
|Raspberry Aventurine with Aventurescence or an Aventurescent Effect|
For iridescence, I go to Miriam Webster. "... a lustrous rainbowlike play of color caused by differential refraction of light waves (as from an oil slick, soap bubble, or fish scales) that tends to change as the angle of view changes" Iridescence can be seen in stones like ammolite and rainbow obsidian, but also in fine pearls.
|Ammolite with Iridescence or an Iridescent Effect|
So, adularescence is interchangable with shiller, or, schiller as it sometimes spelled. Chatoyancy, labradorescence, opalescence, aventurescence all describe the type of shiller in different stones. And, iridescence describes a colorful oil on water type sheen. It is seen ON the stone and not IN the stone, as in adularescence.
I don't know about any of you, but I have used these wrong quite a few times. I shouldn't make that mistake again. Now I know which beautiful word to use. :)
Thanks for reading and enjoy the day.