(IDEX Online) - TAG Heuer has unveiled a new version of its most expensive watch, the Carrera Plasma, to mark its diamond anniversary, incorporating 15.5 carats of lab growns.The gems are step-cut into "imaginative shapes" and set into both the black aluminum case and into the strap. The watch's dial is a polycrystalline diamond plate - a sum of crystals grown as one, and the crown is a single, custom-cut diamond of 2.5 carats.The new Carrera Plasma Diamant D'Avant-Garde Chronograph Tourbillon 44mm is not the first TAG Heuer timepiece to feature lab growns.But it has more carats than any previous watch, and with a $575,000 price tag, it is the most expensive.In April the company launched a version of the same watch with a distinctive 1.3-ct CVD lab grown pink diamond as the winding crown, engraved with its logo, for $376,000.