Diamond miner Lucapa has plucked the biggest-ever gem-quality coloured diamond from its Lulo project in the central-west African country of Angola.

Lucapa recovered a 46-carat pink diamond (pictured above) — which eclipses the 43-carat yellow gem recovered from the Angolan project in January this year and the 39-carat pink diamond found in September 2016.

In November auction house Sotheby’s put up for sale the biggest-known cut pink diamond — a stone called The Raj Pink — which weighed 37.3 carats and was mounted on a ring. The pre-sale estimate was $US20 million to $US30 million — but it failed to sell.

Lucapa’s recovered its 46-carat uncut pink diamond — along with other “large specials” as Lucapa calls them — from a Lulo site called Mining Block 4.

Lucapa is planning to dig out a resource there this year to include in its alluvial JORC resource update.

JORC refers to the mining industry’s official code for reporting exploration results, mineral resources and ore reserves, managed by the Australasian Joint Ore Reserves Committee.

Lucapa is trying to pinpoint the primary hard-rock source or sources of the “exceptional size and quality” alluvial diamonds being recovered from Lulo.

Shares gained 3.8 per cent to trade at 27.5c on Thursday morning.

Diamond prices ‘roughly stable’

Polished diamond prices continued a downward trend in 2016-17, “reflecting soft consumer demand for diamond jewellery across key markets”, according to Bain & Company’s annual diamond report released in February.

Global sales of diamond jewellery were “roughly stable”, held back by flat sales in the US — the world’s biggest market.

The outlook was “stable across the different segments of the value chain”, but the industry faced “three key, persistent challenges” according to Bain:

Soft demand for diamond jewellery driven by competition from other luxury goods and experiences
A “mounting risk” that lab-grown diamonds will legally or illegally erode the market share of natural diamonds
The financial stability of diamond players amid price volatility.