Zambian Emerald Parcel, 4 to 8 cts

Buying this parcel

Where it came from, what its weight band is for, and what to check before any money changes hands.

The deposit

Zambian emerald forms where beryllium-bearing pegmatite veins cut through schist rich in chromium and vanadium, and the colour is made only in the narrow reaction zone along that contact. That geometry is why size matters so much here. The zone is thin, the crystals growing in it are constrained by it, and rough clean enough to survive cutting above four carats is a far smaller fraction of Zambian production than the weights below it would lead you to expect. A parcel with a raised floor has therefore been selected out of a great deal more material than its own size suggests.

This parcel

Nothing in this parcel is under four carats, and that floor is the entire point of it. Four carats is roughly where an emerald stops being an accent and becomes something that can carry a ring on its own, so every stone here is a candidate centre rather than a supporting piece. Most are step cut, which is what beryl’s hexagonal habit invites and what shows the body colour cleanly instead of chopping it into flashes, and it also means they run deep: check how much of the weight sits below the girdle before comparing two stones on carats alone. If you want small matching stones to set around one of these, that is the two to eight carat parcel instead, and the two are usually bought together.

Treatment

Unheated and untreated, stated for every stone in the parcel rather than for a representative sample. Larger emeralds are where filling is most tempting commercially, because a fissure that would be invisible in a one carat stone is plainly visible in a five carat one, so the absence of it in this band is the thing worth paying for. Ask us to submit any stone you select for a report before purchase and we will, rather than asking you to take the parcel’s word for it.

The report

No report is held for this 4 to 8 cts emerald parcel yet, and we would rather say that than name a laboratory that has not seen it. We will submit whatever you select to IGI or IIGJ before purchase on request.

Before you pay

• Judge these one at a time against a white ground. At this size the eye starts compensating for a neighbouring stone’s colour.
• Check the depth. A deep-cut emerald weighs more than it looks and will sit high in a mount.
• Look at the corners on any step cut. Emerald corners are where the chips are, and they are usually why a stone is cheap.

Read next

Panna, the emerald covers the material itself and what gets sold in its place. How to buy a coloured stone covers pricing, treatment and reports.

Written by Kamal Kishore Agarwal, founder and gemmologist, Gem-A qualified, buying in Johari Bazaar since 2008.