New gemstone sources are expanding market supply, with Columbia Gem House launching sapphires and rubies from Tanzania and Auctim.com hosting an auction of over 1.4 tonnes of rough Brazilian emeralds.

Columbia Gem House’s collection of untreated sapphires and rubies come from the Winza and surrounding mining regions in central Tanzania. The new inventory features an extensive colour range, including vivid pinks, saturated purples, fuchsia, Padparadscha and rubies. 

According to the gemstone wholesaler, the sapphires and rubies are fully untreated, with many pieces exhibiting natural bicolour zoning due to chromophore variation within a single crystal. This includes combinations of red and blue, some of which result in striking bicolour and kaleidoscope gemstones.

The initial offering includes rounds, baguettes, pears and marquise shapes in calibrated sizes of 4.5mm and under. 

"Establishing a dependable supply chain for this material has been an important project for us," said Columbia Gem House’s sourcing team. "This material meets our standards for traceability and offers exceptional quality. We are particularly excited about offering clean, richly saturated pink sapphire in a market where untreated material is increasingly rare."

Meanwhile, Auctim.com will hold an online auction in September featuring 1,463.3 kilograms of rough Brazilian emeralds, offered across 109 lots. 

Spanning from commercial melee to vibrant near-gem stones, the collection is offered as part of a court-ordered liquidation.

Auctim CEO Christophe Moyersoen said, “This sale stands out due to both the volume and the variety. In addition to commercial-grade parcels, bidders will also discover premium material with strong cutting potential and colour appeal.”

In-person viewings are available in Antwerp and limited to verified B2B bidders who have completed the registration process. Bids will be accepted from September 1 to 11.