MY PRECIOUS ONE! AN IRRIDESCENT BOULDER OPAL GEMSTONE FROM AUSTRALIA WITH A BEAUTIFUL PLAY OF COLOUR - PLEASE READ DESCRIPTION

A BEAUTIFUL 1,10CT (0,22G PLEASE SEE PHOTO MULTIPLY WEIGHT BY 5 TO GET CARATS) BOULDER OPAL GEMSTONE FROM AUSTRALIA. BOULDER OPAL IS A UNIQUE TYPE OF OPAL THAT IS ONLY FOUND IN QUEENSLAND AND IS ONE OF THE MOST SOUGHT AFTER TYPES OF AUSTRALIAN OPALS. IT IS A RARE GEMSTONE AND THE ONLY ONE IN THIS COLLECTION.
 
THIS PARTICULAR STONE WAS BOUGHT IN 2011 FROM AN ONLINE SELLER WITH THE ORIGEN OF THE STONE INDICATED AS AUSTRALIA. IT WAS ALSO SOLD AS A NATURAL BOULDER OPAL GEMSTONE.
 
Boulder opal has an attribute like no other due to its formation in fractures and spaces in an sandstone or ironstone (form of porous shale) host rock. The opal is usually formed in thin veins through the ironstone and has to be opened or split to find the face of color.  was discovered in Australia, in about 1870. It is the second most valuable type of opal, however remains largely unknown to the general international public.
 
BECAUSE BOULDER OPAL FORMS IN THIN VEINS IN IRONSTONE BOULDERS, THE HOST IRONSTONE IS USUALLY LEFT ON THE BACK OF THE STONE. THIS IS WHY, IF YOU LOOK AT THE BACK OF A BOULDER OPAL, THERE IS A LAYER OF BROWN ROCK ATTACHED TO THE BACK. FOR THIS REASON, BOULDER OPAL IS SOMETIMES REFERRED TO AS A NATURAL DOUBLET, AS THIS LAYER OF DARK STONE ON THE BACK GIVES THE OPAL ITS DARK BODY TONE.
 
TESTS PERFORMED:
UNCLEAR ELECTRON UV (LONGWAVE) LIGHT EMISSION TEST: INERT WITH PINKISH SPOTS UV LIGHT REACTION (PLEASE SEE PHOTO).
Many specimens of opal display fluorescence under shortwave (100nm - 280nm wavelength) ultraviolet light. A smaller number will display fluorescence under a longwave (315nm - 400nm wavelength) ultraviolet lamp. Some specimens do not show noticeable fluorescence at all.
Most of these opals exhibit a green fluorescence, but blue and white fluorescing opals also occur.
 
SIZE: 8,0mm x 5.0mm x 3,0mm
 
MY PERSONAL CONCLUSION REGARDING THIS GEMSTONE:
VISUALLY THIS BOULDER OPAL LOOKS VERY SIMILAR TO SAMPLES I SAW ONLINE. PLEASE HAVE A LOOK ONLINE AS WELL.
Composition Opals, Synthetic Opals and Imitation Opals are however regularly encountered. They will often have an overly shiny appearance, and the colour flashes will be repeated in an organised pattern.
MY CONCLUSION:  MY HEART AND EYES INDICATE THIS JUST MIGHT BE A NATURAL BOULDER OPAL GEMSTONE 
 
DISCLAIMER: I AM NO GEMSTONE EXPERT AND NONE OF THE PRELIMERY TESTS I COULD PERFORM (SCRATCH TEST; UV TEST; THERMAL TEST) CAN CONFIRM THIS GEMSTONES NATURE AND PROPERTIES. THIS GEMSTONES BELONGED TO A FAMILY MEMBER THAT HAS PASSED AWAY. HE COLLECTED GEMSTONES DURING THE EARLY TWENTY FIRST CENTURY MANY WERE BOUGHT ON EBAY AND OTHERS BY TRAVELLING TO OTHER COUNTRIES. ADVANCED INTRUMENTS ARE NEEDED TO DISTINGUISH ONE GEMSTONE FROM ANOTHER AND TO CONFIRM IF IT IS NATURAL OR LAB MADE.
 
PRECIOUS BOULDER OPAL:
OPALS ARE MADE OF SILICA SIO2 WITH UP TO 20% WATER. THEY DO NOT POSSESS A CRYSTALLINE STRUCTURE AND SPECIFIC CHEMICAL COMPOSITION AND IS CLASSIFIED AS A MINERALOID IN STEAD OF A MINERAL. 
Opals form when a hot silica rich solution permeates veins and voids in the ground and the solution precipitates at low temperatures allowing the gradual formation of layers of minute silica spheres. These regularly stacked, three-dimensional groups of spheres give rise to an optical phenomena called PLAY OF COLOUR which causes patches of spectral colour firing from the opal as it is tilted in the light.
When Opal display these flashes of vibrant rainbow colours it is called Precious Opal as to Common Opal (Not iricdescent but anything but common) and Fire Opal (Fire opal is translucent with a bodycolor that is usually yellow, orange or red).
THE PLAY OF COLOUR SHOWS OFF MUCH BETTER ON A DARK BACKGROUND. AS A RESULT, BLACK PRECIOUS OPALS ARE DEEMED MORE BEAUTIFUL AND ARE MORE SOUGHT AFTER. MOREOVER OPAL IS OFTEN STILL ATTACHED TO ITS HOST ROCK AND IS THEN CALLED BOULDER OPAL. The beauty and mystery of this optical phenomenon made opals one of the most precious gems in Antiquity and the Middle Ages. They are sometimes referred to as the queens of gemstones.
THERE ARE ONLY FEW LOCALITIES WHERE BLACK OPALS ARE FOUND. THE MAIN ONE TODAY IS AROUND LIGHTNING RIDGE IN NEW SOUTH WALES, AUSTRALIA WHERE THE FIRST BLACK OPAL IS THOUGHT TO HAVE BEEN FOUND IN 1877. ETHIOPIAN OPALS ARE A MORE RECENT FIND.
Probably the most famous black opal in history called the Burning of Troy owes its name to the blazing red flashes burning in the black gem. It was gifted by Emperor Napoleon to his wife Joséphine, his beloved Helen. Now lost, it was regarded as the most beautiful and most valuable black opal, weighing 700 carats. It is believed it was mined in Honduras.
 
PLEASE ALSO SEE MY OTHER ITEMS LISTED. I HAVE VARIOUS OTHER GEMSTONES ON AUCTION THIS WEEK. COPY THE URL UNDERNEATH AND PASTE INTO GOOGLE AND IT WILL TAKE YOU DIRECTLY TO ALL MY LISTINGS THIS WEEK. 
https://www.bidorbuy.co.za/seller/3685641/ErnRex1545