The Buyer
Type IIa Diamonds
The nitrogen-free 1.8% — the purest diamonds nature makes, the most sought after of all, and the names that set records at auction.
A natural Type IIa diamond is worth a great deal more than a comparable Type Ia stone — and the reason lies in what the crystal does not contain. Almost every diamond holds traces of nitrogen woven into its lattice; the Type IIa stones are those grown essentially free of it. That single absence makes them the most chemically pure diamonds nature produces.
The 1.8%
They are also extraordinarily rare. Type IIa diamonds account for only about 1.8% of all diamonds, and that scarcity, joined to their particular excellence, makes them among the most sought after stones in the world. The purity has a visible consequence: free of nitrogen, these diamonds can reach the highest, most transparent ranges of colour, the water that collectors prize above all.
| Type Ia | Type IIa | |
|---|---|---|
| Nitrogen | Present (the common case) | Essentially none |
| Share of all diamonds | The great majority | About 1.8% |
| Reputation | The everyday diamond | The purest, most coveted |
Records and colour
Because they are so few and so fine, Type IIa diamonds regularly achieve records at auction — many of the great historical stones, and a large share of the largest modern ones, fall into this class. The connection runs further still: most fancy-coloured diamonds are Type IIa as well, their colour arising not from chemistry but from structure. The same purity that yields the most flawless whites underlies many of the rarest colours the earth has ever sent up.
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