The Journal

Notes on
colour.

What we learn at the bench, at the sorting table and on buying trips. Written for collectors who want to understand a stone before they own it.

A pile of rough emerald crystals from Nigeria, pale bluish green six sided prisms with fine lines along their length, on a black leather surface

Latest · Gem knowledge

Nigerian emerald. What it is, where it comes from and how to buy it.

Nigeria is a small emerald producer with a big range of colour. Its stones run pale to medium green, some lean blue, and the line between emerald and green beryl matters more here than anywhere.

20 September 2026 6 min read

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Gemstone shapes and cut chart showing oval, pear, cushion, rectangular, trilliant, heart, marquise, round, square and fancy outlines beside real cut stones

Buyer education

19 September 2026 8 min read

The 4Cs of coloured gemstones. What matters, and in what order.

Diamond grading gave us the 4Cs. Coloured stones use the same four words with different rules. Colour comes first, and carat weight does not tell you the size.

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A deep blue violet cushion cut tanzanite in front of a purple ink splash on a white background

Gem knowledge

16 September 2026 7 min read

Tanzanite. One mine, one colour and how to judge a stone.

Tanzanite comes from a single small area in northern Tanzania. Heat creates its blue and the cutter's angle decides how much of it you see. Here is how to buy one well.

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Three long emerald cut green tourmalines standing upright, each shading from lime green at the top to cool blue green at the base

Gem knowledge

13 September 2026 7 min read

Green tourmaline. Why one gem comes in so many greens.

Iron, chromium and vanadium each paint a different green. Tourmaline also changes colour along its length, and the cutter decides what you see. Here is how to choose well.

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Two faceted blue green serendibites, one octagonal and one rounded, on a pale blue background

Rare gems

11 September 2026 6 min read

Serendibite. Found in Sri Lanka in 1902 and still almost never seen cut.

Serendibite carries a boron rich chemistry that almost never forms, and the few cut stones weigh well under a carat. Here is what it is, where it comes from and how to buy one.

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Three deep blue benitoite crystals sitting in pale grey and white host rock

Rare gems

10 September 2026 6 min read

Benitoite. California's state gem and a blue that glows under UV light.

A prospector mistook it for sapphire in 1907. Benitoite has fire close to a diamond, glows under ultraviolet light and comes from a single mine in California.

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Six faceted orange, salmon and pink gemstones in emerald, cushion, pear and step cuts on a dark reflective surface

Rare gems

9 September 2026 6 min read

Vayrynenite. A soft, fiery gem that almost never passes one carat.

Vayrynenite forms in a few pegmatites and glows orangey red in the right light. Almost every cut stone weighs under one carat, and the gem scratches easily.

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Four Ethiopian copper-bearing tourmalines in vivid blue: an emerald cut, a rough-cut cushion, a pear shape and a large rough stone

Market watch

8 September 2026 6 min read

Ethiopia joins the paraiba map. What that means for buyers.

Two major laboratories confirmed Ethiopia as a source of copper-bearing tourmaline in August 2026. The name is now settled. The price is not.

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A large diaspore crystal lying on a black reflective surface, with three cut colour change stones in front of it showing green and orange tones

Rare gems

7 September 2026 6 min read

Zultanite. A colour change gem from one mountain range in Turkey.

Zultanite shows green in daylight and pink under a warm bulb. It cleaves easily, so cutters lose a lot of rough and finished stones ask for gentle wear.

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