Gemfields unveils 40-carat ruby from Mozambique

Gemfields recently uncovered this 40.23-carat rough ruby from its Montepuez mine in Mozambique. London--Gemstone miner Gemfields discovered a 40.23-carat ruby--which it has called “one of the most important rubies unearthed in recent times”--at its Montepuez ruby deposit in Mozambique.

The Gübelin Gem Lab in Switzerland has appraised the piece of rough ahead of Gemfields’ December auction in Singapore, with Gübelin Managing Director Daniel Nyfeler noting in a statement that, “Although difficult to judge in the rough state, the transparency and color of the crystal indicate an important gemstone might be cut from this piece of rough. We are looking forward to following the development of this remarkable rough from its current state to a cut gem.”

It is not currently known if this is the largest rough ruby Gemfields has recovered from its Montepuez ruby mine to date.

Ruben Bindra, a member of the American Gem Trade Association’s board of directors and president of B & B Fine Gems, told National Jeweler that this piece of rough “can actually be of great importance.”

While the yield from the rough depends on a number of factors, including the shape, inclusions, and the nature of the crystal, “conservatively one may assume yield of 30 percent to 40 percent. This should provide you with a 12- to 16-carat gem,” he said. 

The important questions in this case, he adds, would be how clean the stone is and whether or not it requires heat treatment. 

A clean stone that doesn’t need to be heated is, of course, more valuable. If this is the case here, this piece of rough could yield a cut and polished ruby with a wholesale value of $1.5 million or more, Bindra said.

The stone also is significant because it attests to the mine’s ability to produce important rubies, he said, adding that, “The market is also in need of such material as very little is trickling out of Burma.”

Gem dealer and AGTA board of directors member Jeff Bilgore added, “It's a very rare rough gemstone, and it's a fantastic discovery,” noting that, due to the rarity of rubies, the discovery of a 40-carat ruby to comparable to finding a 100-carat rough diamond or more. 

He also said, however, that origin has a lot to do with value. Though it is a good discovery, a Mozambican ruby still doesn’t carry the same value as a Burmese ruby.