HOW STRANGE? A LARGE 17,30CT GREEN AMETHYST GEMSTONE WITH BEAUTIFUL CUSHION CUT

AN AWESOME LARGE 17,30 CARAT (3,46G MULTIPLY WEIGHT BY 5 TO GET CARATS) GREEN AMETHYST QUARTZ GEMSTONE WITH A BEAUTIFUL OVAL FACETTED CUT. EVERYBODY KNOWS AMETHYST IS PURPLE HOW CAN IT BE GREEN? NATURAL GREEN QUARTZ IS USUALLY CREATED FROM HEAT TREATING SOME VARIETIES OF QUARTZ, MOSTLY AMETHYST. THIS ASSOCIATION SEEMS TO PERMIT THE USE OF THE MISNOMER GREEN AMETHYST.
 
THIS PARTICULAR STONE WAS BOUGHT FROM A SELLER IN MOSSEL BAY SOUTH AFRICA WITH THE COUNTRY OF ORIGEN INDICATED AS BRAZIL. IT HAS A VVS (EYE CLEAR) CLARITY WHICH MEANS IT IS FREE OF INCLUSIONS AS SEEN WITH THE NAKED EYE WHICH IT APPEARS TO BE. IT WAS ALSO SOLD AS A NATURAL GREEN AMETHYST GEMSTONE THAT WAS NOT HEAT TREATED.
 
TESTS PERFORMED:
PASSED SCRATCH TEST: IT DID SCRATCH A GLASS WINDOW PANE EASILY WHICH WOULD INDICATE IT IS HARDER THAN GLASS. (MOHS HARDNESS GLASS 5.5-6.5, QUARTZ 7.0-7.5)
PASSED UV LIGHT TEST: INERT NO UV REACTION. (THE UV LIGHT HIT THE ELECTRONS. THEY JUMP AND FALL BACK. THEY RADIATE LIGHT OF A CERTAIN WAVELENGTH WHEN THEY DO WHICH IS SPECIFIC TO EACH ELEMENT IN THE MINERAL. THIS IS CALLED FLUORESCENCE.) ONLY 10% OF GEMSTONES EXHIBIT A FLUORESCENCE AFFECT LIKE RUBIES, SAPPHIRE, TOPAZ, OPALS AND DIAMONDS. GLASS AND ALL NATURAL QUARTZ VARIETIES DOES NOT SHOW A UV AFFECT.
PASSED THE THERMAL CONDUCTIVITY TEST: TESTED THE THERMAL CONDUCTIVITY WITH A MIZAR PRESTIGE SERIES 2 DIAMOND TESTER. IT MOVED UP THE LADDER FROM STANDARD LEVEL 3 TO LEVEL 4. FOR QUARTZ A LEVEL OF 4 IS THE NORM FOR THIS TESTER.
(WITH THIS TESTER GLASS 0,002, TANZANITE, TITANITE AND TOURMALINE MAKES NO MOVEMENT, AQUAMARINE AND EMERALD LIE INBETWEEN AND CAN GIVE A LEVEL OF 3 OR 4. QUARTZ 0,026, GARNETS, SPINELS 0,028 AND KUNSITE GIVES A THERMAL OF 4, TOPAZ 0,04 GIVES A THERMAL OF 5. RUBIES AND SAPPHIRE 0,08 GIVES A THERMAL OF 6 TO 7.)
 
SIZE: 18.5mm x 15,2mm x 9,9mm
 
MY PERSONAL CONCLUSION REGARDING THIS GEMSTONE:
COMMON QUARTZ IN ITS NATURAL STATE IS COLORLESS, THOUGH TRACE ELEMENT IMPURITIES CAN IN RARE INSTANCES MAKE IT PALE BLUE OR GOLDEN BROWN TO YELLOW ORANGE. QUARTZ IS OFTEN TREATED WITH HEAT OR RADIATION TO MAKE IT A DEEP BLUE, REDDISH-ORANGE, PALE GREEN, PINK, OR EVEN PURPLE. NATURAL GREEN QUARTZ IS USUALLY CREATED FROM HEAT TREATING SOME VARIETIES OF QUARTZ, INTERESTINGLY MOSTLY AMETHYST.
ALTHOUGH SYNTHETIC QUARTZ EXIST AND IS RATHER COMMON NATURAL QUARTZ IS ABUNDANT. IN FACT, SYNTHETIC QUARTZ CAN BE SEEN SOLD AT A VALUE MORE THAN NATURAL HEAT TREATED QUARTZ.
MY CONCLUSION:  IT IS PROPABLY A NATURAL AMETHIST QUARTZ GEMSTONE THAT HAS BEEN HEAT TREATED
 
DISCLAIMER: 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. I AM NO GEMSTONE EXPERT AND COULD ONLY PERFORM SOME PRELIMINARY TESTS - ADVANCED INTRUMENTS ARE NEEDED TO DISTINGUISH ONE GEMSTONE FROM ANOTHER AND TO CONFIRM IF IT IS NATURAL OR LAB MADE.
 
NATURAL OR SYNTHETIC
Given the low price for natural quartz varieties, it may come as a surprise that there is a large industry producing synthetic quartz using a method known as hydrothermal transport and recrystallization. Though the cost of producing synthetic quartz is more than mining natural quartz, a large industry has developed to create synthetic quartz.
Small fragments of quartz that act as a source material are placed on the bottom of a container and acts as numerous small seed crystals of quartz. This method was designed to produce colorless quartz for industrial applications. But it is also possible to grow synthetic quartz in colors not found in nature, including unusual multicolored combinations.
 
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https://www.bidorbuy.co.za/seller/3685641/ErnRex1545