It’s party season for watch collectors and enthusiasts, and two of the world’s most prominent luxury watch brands – Audemars Piguet and Cartier – are celebrating their 50th anniversary by not only releasing a collection of watches, but taking things up a notch with collectible timepieces and limited editions.

Double rainbow: Audemars Piguet Royal Oak

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The new Royal Oak Selfwinding is available in not one but two sets of 10 – in 37mm and 41mm – each absolutely smothered in baguette-cut gemstones of a particular hue: about 800 of them per watch. With watches in each set in red, orange, yellow, pink, green, purple and blue, the stones used to decorate them took about a year to select, and include rubies, emeralds, blue sapphires, tanzanites, yellow chrysoberyls, pink tourmalines, amethysts, blue topaz, orange spessartites and tsavorites.

Rock on: Cartier Pebble

Most watches are predictably shaped. That has never been true, though, of the Cartier Pebble. A genuine exception among the codes of luxury watchmaking, it fits a square dial with rounded corners, offset at an angle of 45 degrees, inside a round case that, as the name suggests, takes its design cues from the curves of a pebble.

This year, the collection celebrates 50 years since the watch was first unveiled as part of a blaze of innovation from the maison during the late 1960s and early 1970s – and to mark the occasion, Cartier has produced a rendition that closely follows the aesthetics of the original, with a few subtle modifications. Key updates include the 430 MC calibre that powers it – one of Cartier’s flattest hand-wound movements.