The Only Watch auction is a highlight of the horological calendar, and brings together some of the biggest names to create unique timepieces, and all for a good cause. Now in its ninth iteration, the biennial auction was founded by Luc Pettavino in 2005 to help fund a cure for Duchenne muscular dystrophy, a muscle-wasting disease that primarily affects boys, and that has no cure to date. Under the patronage of Prince Albert of Monaco, watchmakers from around the world create – and then donate – one-off masterpieces purely for the auction, making it a unique event for manufacturers, as well as collectors. Drawing collectors from across the globe, the next auction is scheduled for November 6, and is sure to sell out. To date, the auction has raised €70 million ($83m), with 99 per cent of the money going directly to fund research into the disease that affected Pettavino’s son, Paul. With the line-up of the new one-of-a-kind timepieces now announced, we take a peek at 10 of the most fascinating. <b>Scroll through the gallery above for some of the timepieces to be auctioned at Only Watch 2021.</b> This is the last unique 15202 reference timepiece to be powered by Calibre 2121, that at only 3.05 millimetres, is the thinnest automatic movement of its kind. Featuring a 39mm sandblasted titanium case, it also has a polished Bulk Metallic Glass bezel, made by rapidly cooling palladium alloy, in a first for the house. In a break from the norm, this piece is made almost entirely from transparent sapphire crystal, with the case machined from three blocks and the dial from six. The result is an almost 3D skull image that rises in Only Watch orange. A new addition to Boucheron’s long history of bestiary, this charming 38mm case carries a chameleon, picked out in diamond, multicoloured sapphire, tsavorite and ruby on white gold. The workmanship is remarkable both on the face and the reverse, while the curving body of the creature frames the mother of pearl dial. Offered as a pair, these complimentary J12 ceramic timepieces are a tribute to the success of the J12, launched in 2000. Presented in sharp monochrome, this pair also has a special black finish. Using the Only Watch orange, Hublot has created a skeleton tourbillion, set within a transparent case. At 45mm, the case is cut from clear, and orange sapphire crystal, with the same material used to make five out of the 42 components of the movement. This bold watch features an automaton instead of hands, that is solely powered by the movements' mainspring. Stemming from a conversation with film director Francis Ford Coppola in 2012, this uniquely innovative watch arrives in a 42mm case of rose gold after seven years in development. Inspired by a 1910 desk clock by Faberge, this delicate 36mm rose gold timepiece has a white mother of pearl face, and a hand-engraved central dial, inset with ruby "shooting stars". Engraved with the words "Choose Hope” on the face, it echoes the ethos of Only Watch itself. The face of this enigmatic looking 40mm timepiece is in Vantablack, a compound that is officially the blackest black in existence. It retains its air of mystery by tipping the hands at a 45-degree angle, so that only the wearer can read the time. Using all the the house's famed skill, this timepiece has a dial made of different, hand enamelled plique-a-jour pieces. In shifting tones and colours, it is made to resemble a modern stained glass window. With an off-centre dial at 6 o’clock, and a tourbillon at 12 o’clock, both follow the stark geometric lines of the skeleton movement. Originally developed for the Formula One driver Charles Leclerc to be a second skin, this 47.25mm, extra flat case is made from red and white Quartz TPT, a composite exclusive to Mille. With a seamless strap for extra comfort, the watch has numerous red details, in a nod to Leclerc’s role at Scuderia Ferrari.