Rubellite
Manganese
Pink to red. The finest hold their colour under artificial light instead of turning brown.
The colour range
No mineral holds more colour
Tourmaline is not one mineral but a family, and its structure will accept almost any element that happens to be in the melt around it. Iron, manganese, chromium, vanadium, copper — each leaves a different colour behind. That is why the merchants of Ceylon gave it a name that simply meant mixed stones: they could not sort it, because it arrived in every colour they knew.
How to judge it
Four things, in this order
01
Hue
Which colour it is, and what else is mixed into it. Almost every tourmaline carries a secondary hue — a green with yellow in it, a pink leaning orange. Name both.
02
Saturation
How free the colour is of grey. This is what separates a fine stone from a common one, and it is the hardest thing to judge from a photograph.
03
Tone
How light or dark. Most buyers assume darker is better. In tourmaline it usually is not — past a certain tone the stone closes and stops returning light.
04
Behaviour in light
Take the stone out of the shop lights. Fine rubellite holds its red under incandescent light; ordinary material turns brown. Cuprian material keeps glowing in shade.
The neon
Why some tourmaline appears lit from inside
Neon is not a poetic word here. It describes a measurable behaviour: the stone returns a narrow, almost single colour and keeps returning it when the light around it drops. Ordinary saturated tourmaline goes flat and dark in shade. Cuprian material does not.
The cause is copper. Divalent copper, Cu²⁺, absorbs broadly in the red and the near infrared — bands centred around 700 and 900 nanometres — and leaves the blue-green part of the spectrum almost untouched. What reaches the eye is a clean, narrow band with very little of the grey that iron introduces into most other gems. That absence of grey is what reads as glow.
Manganese decides where in the range the stone lands. Trivalent manganese, Mn³⁺, absorbs near 515 nanometres and adds a violet to purple component; with copper it produces the purple material that comes out of the ground. Low-temperature heating converts Mn³⁺ to Mn²⁺, which barely absorbs in the visible range at all: the 515 nanometre band disappears, the copper band stays exactly where it was, and the stone moves to blue or blue-green. This is why nearly all Paraíba on the market has been heated, and why the treatment is accepted — it removes an absorption, it does not add a colour.
A correction the trade keeps getting wrong
Paraíba is not only blue
The definition agreed by the world's major laboratories covers a range, not a colour: blue — electric blue, neon blue, violet blue — bluish green to greenish green, green, and yellowish green, at medium-light to high saturation and tone, coloured mainly by copper and manganese, of whatever geographical origin.
So a mint or neon green cuprian elbaite is a Paraíba tourmaline, fully and correctly named — the great majority of green Paraíba on the market comes from Mozambique. What differs is price, not legitimacy: electric blue is scarcer and trades at a large premium over green, and the market conflates that premium with the definition. They are separate things, and we keep them separate.
Where the name stops
Copper is necessary but not sufficient. The same standard sets two limits that most sellers never mention, and both exist to stop weak material borrowing the name.
Traces are not enough
Tourmaline with only traces of copper, or with colour saturation below the range, is not called Paraíba — even though the chemistry technically shows copper. A pale, washed stone with a copper reading does not qualify.
Too much iron and it is out
Iron-rich copper-bearing tourmaline whose polarised o-ray spectrum shows the 700 nanometre band higher than the 900 nanometre copper band is excluded by name. In plain terms: if iron is doing more of the work than copper, the stone is a tourmaline that happens to contain copper — not a Paraíba. This is the line that separates a genuine cuprian gem from the green material sold at its price.
Reports name the origin as Brazil, Nigeria, Mozambique, other, or undetermined — and the definition itself is origin-blind. Anyone charging a Brazilian premium is charging for the origin line on the report, not for the word Paraíba.