Loose Jeremejevite Gemstones Online At Wholesale Prices. Gem Rock Auctions has a collection of extremely rare loose Jeremejevite crystals available direct to the public. It is a rare mineral from the borate class and due to it’s scarceness is very rarely found in jewellery. It is a colourless, sky blue or pale yellow mineral and originates from the Erongo Region in Nambia. It is one of the gemstones that is highly sought after by mineral collectors and gem collectors alike.