Arnold & Son has a background of using out-of-the-ordinary materials in its watches, from meteorites to rare pearls.
The latest Double Tourbillon continues this philosophy with a dial made from a rare semi-precious gemstone called charoite.
The name comes from Russia’s Chara River, where charoite was discovered in the mid 20th century.
The gemstone gives the dial a captivating purple color with white speckling.
The purple dial contrasts with the twin white opal subdials alongside the signature double tourbillon and the hand-finished white gold tourbillon bridges.
The twin dials show the local hours and minutes at the top in Roman numerals, and independent reference hours and minutes below in Arabic numerals.
The 43.5 mm case is made from 18k white gold.
The hand-wound 3Hz mechanical movement has a 90 hour power reserve.
It has a domed anti-reflective sapphire crystal, along with a sapphire caseback for admiring the movement from beneath.
The Double Tourbillon White Gold, Charoite Edition, comes on a purple leather strap and is water-resistant to 30m.
The one-off piece costs CHF 227,100 (c. £204,000)