The Gem Portal is selling a greenish-blue Paraíba tourmaline at a live online auction, with a starting bid of $1.

The lot, an 8.31-carat Mozambique gemstone, will go on offer with no reserve and sell to the highest bidder in the October 14 sale, The Gem Portal said Monday. The low starting price and no-reserve format let bidders determine the stone’s value, with dealers, collectors, and jewelers competing in a transparent live auction where the highest bid wins.

Bangkok-based gemstone dealer The Gem Portal specializes in sourcing high-quality colored gemstones, which it sells through its store on the Gem Rock Auctions marketplace. — John Bassett