The 5,655-carat stone found earlier this month at the Kagem mine will be sold at auction in Singapore in November, Gemfields Group Ltd. said in a statement on Monday.

The stone is almost twice the size of the world’s biggest ever rough diamond, the Cullinan, discovered near Pretoria in South Africa in 1905. Still, it’s unlikely to be worth anywhere near as much since large emeralds are far more common and are hard to value. For years, Gemfields had a pineapple-sized emerald locked in a safe as it didn’t know how much it was worth.

Emerald prices have climbed in recent years as Gemfields boosted advertising in a bid to expand the market for the green stones. Emeralds were previously mainly produced by artisanal miners, leaving retailers without a consistent supply.

Gemfields, which also produces rubies in Mozambique, was taken over last year by South African commodities investment firm Pallinghurst Resources Ltd. DM