The stones · I
Ruby
Red corundum, coloured by chromium, bought where it comes out of the ground. Everything I write about ruby starts from one rule: no heat, ever.
What I buy
I buy ruby that has never seen a furnace. The laboratory report has to say so in plain words — no indications of heating — from Gübelin, SSEF, GRS or AGL, and the stone has to agree with the paper on the tray. A heated ruby can be beautiful and honestly sold; it is simply not what my clients come to me for, because the premium of the unheated stone is the part of the ruby market that has compounded for thirty years.
Mogok is the reference. Marble-hosted ruby from the Stone Tract is low in iron, so the chromium glows in daylight and the red has a life of its own. Mozambique, from Montepuez, supplies most of the fine ruby on the market today, and the best of it is superb; I buy it on its merits, at its price, never dressed up as something else. Glass-filled, flux-healed and diffused stones do not cross my desk at any price.
The stones that make a collection sit between one and a half and five carats, in a red that holds at three metres. Above five carats, unheated and clean, the field narrows to a handful of stones a year, and that is when the mandate matters more than the market.
How I judge it
- Daylight only, north window, against master stones. The seller’s lamp is off.
- The three-metre test: red, not orange, not pink, from across the room.
- Silk intact under the loupe. Fine rutile needles mean the stone was never cooked.
- No window. Held over print, a well-cut ruby shows colour, not the page.
- Long-wave ultraviolet: a low-iron ruby answers with a red glow; an iron-rich one sits dark.
- Then the paper: origin, treatment line, and whether the laboratory would write pigeon’s blood.
Read further
The guides
Unheated Burmese Ruby
Ruby: Properties, Origins, Treatments and Value
Star Sapphire and Star Ruby: Asterism Explained
Questions collectors ask
Do you buy heated rubies?
No. Every ruby I source carries a laboratory report stating no indications of heating. A heated ruby can be a fair purchase for wear; it is not an asset in the sense my clients mean.
Is Mozambique ruby a compromise?
Not when it is bought for what it is. The finest Montepuez stones stand beside Burmese ruby in a laboratory; the market still pays a durable premium for Mogok, and the price of each should reflect that honestly.
What does an unheated ruby cost?
Per carat, the price rises steeply with size and colour: a clean unheated Burmese stone above three carats is a six-figure purchase, and a pigeon’s blood stone above five carats is auction territory. The mandate fixes the brief before the search begins.
