Tsavorite was unknown until 1967 and has never been found in quantity. It is a green grossular garnet, coloured by vanadium and chromium, and it occurs in a narrow geological belt running through Kenya and Tanzania in crystals that are rarely large. That combination is the reason this reference is a harder sourcing problem than the emerald version alongside it in the anniversary Royal Oak gem set: emerald is scarce but has been mined for millennia and moves in a mature market, while tsavorite has to be assembled from a supply that was not being systematically extracted two generations ago. Setting it in matched baguettes across a dial, a bezel and a full bracelet requires a great many stones agreeing on colour from a material that yields few of any size. Tsavorite is also the brighter of the two greens in the set, because garnet returns more light than beryl and tsavorite is typically free of the inclusions that emerald almost always carries.
The case is 41 mm across and 11.6 mm thick in white gold, with the octagonal bezel gem-set in baguette-cut tsavorites. The height sits above the 10.5 mm a standard selfwinding Royal Oak runs to at the same diameter, and the difference is the setting rather than the movement, since baguettes require channels cut into the metal with material left beneath to hold them. The eight hexagonal screw positions survive, and the continuous run of stones breaks and resumes at each one. The dial is white gold set with baguette-cut tsavorites across its whole surface, with no applied hour-markers. The stones are the dial. The white gold Royal Oak hands are the only element above them. The bracelet continues the setting to the clasp, tapering from the case and closing on an AP folding clasp. Because tsavorite is clean and highly refractive, the dial holds its colour in low light where emerald goes dark, and the broad flat tables of the baguette cut return that colour in solid planes rather than in scattered points. The result is a green that stays green rather than one that shifts toward black as the light drops.
The function set is hours, minutes and centre seconds. There is no date, and the absence is structural: an aperture cut through a continuous stone surface would break the setting at the point where an unbroken run matters most, so the dial is left whole. Centre seconds keeps all three hands on one axis and avoids the second circular break a small seconds subdial would impose. Time is read from hand position against the case, since the dial gives no reference points at all. Tsavorite sits at a middle depth of tone and the white gold hands separate from it reliably, which is a practical advantage over the pale stones in the set, where the hands can flatten into the field. The brightness of the stone helps here rather than hindering, because the light it returns is coloured and the hands are not.
The Royal Oak is the collection Audemars Piguet is built on, and the anniversary gem set is the most concentrated gem-setting the collection has carried. Ten stones were used: tsavorite, emerald, ruby, blue sapphire, tanzanite, blue topaz, amethyst, pink tourmaline, yellow chrysoberyl and orange spessartite. Each was issued at 41 mm at this reference and again at 37 mm at 15554, giving twenty references built on the same construction across two case sizes. Green appears twice, in tsavorite and emerald, which makes those two the only direct comparison the set offers within a single colour. Two further 41 mm references sit outside the anniversary designation and use graded mixtures instead of a single stone, one of black sapphires, tsavorites and smoky quartz, the other of graded blue sapphires with Swiss blue topaz, so tsavorite is also one of the few stones in the set that appears in both approaches. The 15512 takes a different route again within the same anniversary run, using brilliant-cut graded blue sapphires with a diamond-set bezel and retaining the date.
This reference suits a collector who wants green and has looked closely enough at both options to prefer this one. Tsavorite against emerald is a real choice rather than a nominal one: the garnet is brighter, cleaner and more consistent, the beryl is older, more storied and more likely to be recognised across a room. Choosing tsavorite means choosing the stone on its optical behaviour rather than on its name, which is a particular kind of decision and identifies a particular kind of buyer. Its scarcity is genuine and recent, which appeals to collectors who prefer material with a documented and short history over material with a long and partly mythologised one. The 41 mm size is the larger of the two the set offers, with the same stone available at 37 mm. The anniversary designation ties production to the occasion rather than to an open catalogue run.
