Three lagoons, named.

The Kimberley runs one of the largest tides on earth — up to eleven metres twice a day. That water moves an enormous amount of food past a stationary oyster, which is why the shells here grow so large and lay down nacre so quickly. Tallon Reef works a small lease on a two-year cycle rather than pushing for a third graft, so the pearls come out thicker in the coat and rounder than the numbers would suggest.

We have bought from the same three lines here since 2016. Panels are lifted and cleaned roughly every six weeks; the harvest is lifted in one window each year, in the cooler months, and we grade the lot on the boat before it is sorted for sale. Nothing from this lease is bleached, dyed, or polished.

A Tahitian pearl is dark all the way through — the colour is the oyster's own shell lip, not a treatment. What varies is the overtone floating on top of that dark body: the greens and violets people call peacock, or the smoky purple called aubergine. Motu Ahé is a small, deep, cool lagoon, and cool water grows slower, tighter nacre.

French Polynesia dropped its 0.8mm minimum nacre requirement for export in 2017, which means thin-coated pearls can now leave the country legally. We kept the old rule. Nothing we buy from Motu Ahé measures under 1.2mm of nacre, and the measurement is on the report.

Akoya are the small, white, brilliantly reflective pearls most people picture when they hear the word. The bay they come from is cold in winter, and the cold is the point: the oyster slows down and lays nacre in finer layers, which is what produces that hard, mirror-like surface. The best of them are lifted in January and February.

We buy winter-harvested akoya only, and only from lots that measure 0.4mm of nacre or better per pearl. That is the threshold the Japanese laboratories use for their top certification. We do not use the trade name for it, because we did not issue the certificate.