One new dated, realized print landed this week, and it is a ruby. Gemfields sold mixed-quality rough from its Montepuez mine in Mozambique between October 5 and 16, and published the results on October 19: $52.0 million, 90 of 99 lots sold, an average of $564.54 per carat.

That number moves the index ruby row. It does not mean rubies got eight times more expensive. The row changes grade, and we explain why below.

Key Takeaways

→ Gemfields' October ruby auction beat the broker forecast. Revenue of $52.0 million came in above the $41.5 million Panmure Liberum had pencilled in. 90 of 99 lots sold, 90.9 percent (Gemfields; Proactive Investors).

→ Revenue held, the average jumped. February's mixed-quality sale raised $52.9 million at $279.39 per carat. October raised $52.0 million at $564.54 per carat. About the same money for roughly half the carats (Proactive Investors; carat comparison is our arithmetic).

→ The offering was smaller than usual, for a reason. Gemfields and its broker point to operational problems at Montepuez Ruby Mining, in which Gemfields holds 75 percent, and to the lower-quality material now going into the separate Trade Select sales launched in June (Proactive Investors; Gemfields RNS).

→ "Highest in more than a decade" is a press claim. Proactive Investors describes the average as the highest in over ten years. The article shows no series behind it, and our index does not go back that far, so we neither confirm nor repeat it as fact.

The index tracks the 8 reference stones every week. Each row holds until a new dated transaction moves it. This week one row changes: ruby. The other seven hold.

Auction prices realized, not retail. Sources: Christie's, Sotheby's, Gemfields, Bonhams, GemGuide, Pala International.

Notable this week: the ruby row now follows the same rule as the emerald row. Both use the Gemfields sale category closest to the investment end of the market. The June Trade Select average was the only ruby print we had. It now gives way to a better match.

The numbers. June 2026, Trade Select (lower-quality) ruby auction, $66 per carat. February 2026, mixed-quality auction, $279.39 per carat. October 2026, mixed-quality auction, $564.54 per carat. Same mine, Montepuez. Same seller, Gemfields (Gemfields; Proactive Investors).

Why the row moves eight times and the market does not. $564.54 divided by $66 is about 8.6. That is our arithmetic, and it measures the gap between two categories of rough, not a rise in price. Last week's emerald lesson applies in full: an average describes the basket it came from.

The fair comparison. February to October is the like-for-like pair, both mixed-quality. There the average went from $279.39 to $564.54, roughly a doubling (our arithmetic).

What drove it. Two things, both named by Gemfields' broker. Lower-quality rough now goes to the separate Trade Select sales, which lifts what remains in the mixed-quality sale. And Montepuez produced less, so the October offering was small: 102,099 carats offered, against roughly 189,000 sold in February (February figure is our arithmetic from $52.9 million at $279.39).

What we cannot see. We have no grade-by-grade breakdown, so we cannot say how much of the doubling is sorting and how much is buyers paying more for the same stones. Rough prices also do not convert directly into what a cut ruby costs.

1. Taking the cheap stones out raises the average. Move the lower-quality rough into its own sale and the remaining sale's per carat figure climbs even if no buyer pays more for any stone.

2. Flat revenue, doubled average. $52.0 million in October against $52.9 million in February. When revenue barely moves and the average doubles, look at the carats first.

3. Ask for the series. "Highest in a decade" is a claim about a time series. If the series is not shown, treat it as a headline.

→ Gemfields' December Trade Select ruby auction. Panmure Liberum calls it the next test of whether buyers accept the new format. It will also tell us whether the $66 June print was typical for that category.

→ Montepuez output. The broker says Gemfields needs better ruby recoveries at the mine. A small offering flatters the average once. It does not repeat.

→ Saffronart, October 21–22. An online sale in India with Kashmir sapphires, Burmese rubies and Colombian emeralds on the catalogue. We report results, not previews, and only where a per carat price can be derived.

→ Autumn sales in Geneva and Hong Kong. Still the most likely source of new dated prints for sapphire, spinel and Paraiba.

Next time you read that ruby prices hit a record, find three things: which quality category sold, how many carats, and which earlier sale it is compared with. If any of the three is missing, you have a headline, not a price.

— Carat Brief

Carat Brief is editorial. Nothing here is investment, legal, or tax advice. Gemstones are illiquid and require certified verification before purchase. Work with credentialed labs: GIA, AGL, SSEF, Gübelin, Lotus Gemology.

Sources: Gemfields (Auction Results: Mixed-Quality Rubies, October 19, 2026); Proactive Investors (Gemfields' ruby auction beats forecasts as prices hit decade high, October 2026); Gemfields RNS via ADVFN (October 2026); Saffronart sale listing via GJEPC Solitaire. Derived figures are marked as our arithmetic.