Our friend (username Guru) writes from Sri Lanka. I have transferred the post here
Here are the instructions for uploading the photograph of the gemstone: You will have to upload it as attachment
Hello, if u find it difficult to upload photographs, please send to
Blue sapphires from Elahera, Sri Lanka are well known in the international gem trade. They are the look-alike of the renowned Kashmir blue sapphires, the bench mark for blue sapphires in the world. In fact, when the Elahera blue sapphires first entered the international gem market, some of the renowned gem laboratories in the world mis-identified them as Kashmir blue sapphires and issued country-of-origin reports certifying them as Kashmir blue sapphires. The Elahera blue sapphires have the unique velvety blue color, known as cornflower blue color, so characteristic of the famous Kashmir blue sapphires. In fact even the external and internal characteristics of the two blue sapphires are identical in many respects, that led to the confusion referred to earlier.
According to Richard W. Hughes, the world renowned gemologist and author of the book “Ruby Sapphire” the most authoritative book available on a single gem species - Corundum, there is a definite market ranking for sapphire according to the country-of-origin. The market ranking runs as follows :- 1. kashmir 2. Burma 3. Ceylon (Sri Lanka) 4. Everything else.
The price-per-carat of Kashmir blue sapphires can vary from anything between US$ 50,000 to US$200,000 depending on its size and quality. Burma sapphires can have a price-per-carat value ranging between US$ 30,00 - 60,000 also depending on its size and quality. High-quality Sri Lanka sapphires of large size, usually above 50 carats can have an average price-per-carat value of aound US$40,000. Smaller Sri Lanka sapphires of good quality and over 10 carats can have an average value of around US$5,000 per carat.
Guru, your sapphire weighs only around 3 carats and it is still in the rough. When cut and polished it may yield a blue sapphire of only around 2.00 carats or even less than that. Despite the stone having a beautiful cornflower blue/peacock blue color, excellent clarity, and homogenous color like Kashmir sapphires as stated by you, due to its smaller size, the value of the stone will only be around US$500 - 1000 per carat.
Thanks very much for the explanation. Yes, Alahara blue gems in Srilanka are best quality in the world. Please Admin, I have a doubtful stone which has diamond qualities.When give a hug to surface of stone, it removes spray quickly and it has abnormal sparkles also. Is it Diamond ? If it is Diamond, Weight is 100 carats. what may be the value of it please ?
@Guru our marketplace would be ready in about 3 months. I would let u know when it is ready. A lot of IT experts are working behind the scenes to make it the worlds best marketplace.
The image of the white rough stone uploaded by Guru is definitely not a diamond. Diamonds are not found in Sri Lanka, even though the country is blessed and has almost 75 varieties of gem minerals out of the nearly 200 recognized gem minerals found around the world. Main varieties of gem minerals found in Sri Lanka are Corundum (blue sapphire, ruby, pink sapphire, yellow sapphire, padparadscha, white sapphire, star sapphire, star ruby, geuda sapphires), Chrysoberyl (yellow to green chrysoberyl, catseye chrysoberyl, alexandrite, cat’s eye alexandrite), Beryl (aquamarine), Spinel (the most abundant gem mineral found in Sri Lanka - The range in color of Sri lanka spinels are ruby red, pink, orange, shades of reddish brown, purple, blue, bluish green, mauve, greenish black, black to colourless), Garnet (Alamandine, Pyrope-Rhodolite, Spessartine, Grossular-Hessonite), Tourmaline (common colors found in Sri Lanka - yellowish green, dull green, honey yellow brown and rarely blue and bright green. Most abundant yellowish-brown), Quartz (purple-Amethyst, yellow/orange-Citrine, rose quartz, white quartz, brown quartz), Topaz (white), and Feldspar (Moonstone).
The varieties of white gem minerals found in Sri Lanka are white sapphire, white spinel, white quartz, white topaz, white zircon known as Matara zircon and white moonstone. Hence the white rough stone you have uploaded can be any one of these white gem minerals.
Sapphires have a hexagonal bipyramidal crystal habit as seen in the image of a white sapphire mined in Sri Lanka. However most sapphires mined in Sri Lanka have lost this hexagonal bipyramidal shape due to erosion caused over millions of years. The image of the rough stone you have uploaded (Images 3 and 4) have a pyramidal shape at least on one side of the stone and may be an indication that it is a white sapphire.
All varieties of colored spinels are quite abundant in Sri Lanka, but white spinels are very rare. Hence, it is highly unlikely that the rough gemstone is a white spinel. Moreover the crystal habit of spinels are octahedral which is not what is seen in the image.
White milky quartz is commonly found in Sri Lanka, and have a shiny appearance like the rough stone you have uploaded. However, because of their cloudiness and opaqueness such quartz stones have no gem value and are not used as gemstones. The crystal habit of quartz is six-sided prism terminating with six-sided pyramids at the ends, like sapphires. Hence the image you have uploaded may be of a milky quartz crystal.
Colorless and white topaz is also quite common in Sri Lanka. Topaz also forms prismatic crystals ending sometimes in pyramidal faces. However, the type of milkiness found in the image is highly unlikely to be that of topaz.
Colorless zircon known as “Matara Zircon” mined in a village in the Matara District of Sri Lanka, is well known in the international gem trade. When cut and polished the “Matara Zircon” has a brilliance and fire very similar to natural diamonds and was known in the trade as “Matura Diamonds.” Crystals of zircon are tetragonal or square prismatic and dipyramidal. Comparison of the giant white zircon crystal discovered in Embilipitiya with the image of the rough stone uploaded, shows that the unidentified rough stone is highly unlikely to be Zircon.
White moonstone is common in Sri Lanka, and the image of a white moonstone from Meetiyagoda, Sri Lanka shows that it is not morphologically similar to the image of the white rough stone uploaded by Guru. The moonstone gets an opalescent luster only after cutting and polishing, usually as a cabochon.
Hence the rough white stone uploaded by Guru is most likely to be a milky quartz crystal or a white sapphire rough stone. Attached files
Thanks very much for answers. As those answers , I understood All of you are experts in gem field . So please explain me this problem, most of people that do not know the clear answer.  CAN WE GUESS THE GEM BY REFRACTION VALUE ONLY ?  DOES REFRACTION VALUE OF A GEM CHANGE WITH INCLUSIONS OF IT ? ALMOST INCLUSIONS[and chemical composition also] VARY WITH COUNTRIES GEM FOUND.FOR EXAMPLE----WHITE SAPPHIRE GEM REFRACTION VALUE IS 1.77. BUT WITH INCLUSIONS , CAN IT CHANGES TO 1.6 OR 1.9 ? PLEASE GIVE ME ANSWER.