November 10, 2022: Beautiful things, that take time to be designed, built, and preserved, are often astounding. Discovered at the Kagem emerald mine in Zambia in March 2020, the Kafubu Cluster is one such flabbergasting example. And it is being offered for sale at Gemfields’ emerald auction, with bidding closing on November 17, 2022.
This 37,555-gram (187,775 carat) cluster of emerald reveals that it contains very little matrix or other minerals, meaning the piece is almost entirely made up of emeralds, which, given its sheer size and formation, makes this a very rare find indeed.
The Kafubu Cluster is a testament to the high-quality gemstones that can be produced when Mother Nature allows time for the various crystals to form deep within the Earth’s crust. A precise set of remarkable geological and geochemical conditions is required for the formation of these brilliant green gems. Beryllium, essential for the crystallisation of beryl, is one of the most elusive elements in the Earth’s crust (estimated to be about 2 parts per million) and must be carried up to the surface by pegmatites, which, in turn, must come into contact with chromium and vanadium-bearing (ultramafic) rocks in order to attain the desired colour. Not all pegmatites are beryllium-bearing and even fewer are emplaced within rocks that contain adequate chromium.
These factors – coupled with even more specific temperature, pressure and fluid content requirements for its formation – makes emerald extremely rare and remarkably erratic in its distribution.
Zambian emeralds tend to have a higher iron content than emeralds from other origins, which means they are less fragile. High iron content also means fewer surface-reaching fractures and less need for treatments and enhancements.
The cluster is filled with numerous individual and intertwined emerald crystals, displaying their perfect hexagonal structure. It displays all the desired characteristics that an emerald should possess: a vivid green colour overall that glows and shines. It offers different levels of perfect crystallisation, to allow the future cutter to create a collection of gems, from fine quality faceting material to cabochons and beads for everyday fun. It is possible that a customer may decide to preserve this in its natural form or cut the piece to yield tens of thousands of carats of commercial to fine quality cut emeralds.
Kagem is believed to be the world’s single largest producing emerald mine. It is 75% owned by Gemfields, in a model partnership with the Zambian government.
