Tennis 50p (2011)

Tennis is among the lower-mintage designs in the London 2012 set, so circulated coins sell above the common sports. The large open net makes wear easy to judge: sharp knots and a well-defined ball add value, while a flattened ball texture and a scuffed band take it away. Uncirculated coins from the Royal Mint's Tennis coin card or coin cover sell for more again.

With 1,454,000 struck for circulation, the Tennis 50p is the ninth rarest of the 81 ranked 50p designs and has the 48th lowest mintage of all 194 circulating UK designs. That puts it in the Scarce band, for mintages 1,000,000 to 2,499,999.

The next rarer 50p is the Flopsy Bunny 50p, with 1,400,000 struck, and the next more common is the Goalball 50p, with 1,615,500 struck.

Look for a net rather than a player. The band along its top cuts across the coin at an angle, the mesh below is made of knotted cords, and a textured ball hangs in the space above, to the right of the logo. Because most of the coin is net, it is easy to pick out in a handful of change. The logo has the Olympic rings, and the net design has no recorded varieties.

Tracy Baines, a sculptor and jewellery designer from Peterborough, saw the competition pictured in the Guardian with only just over a week left to enter. It became a last-minute rush, but she decided she had nothing to lose, drew four designs, and tennis was the one that won. She chose the sport mainly because her mother is a huge fan, so it was part of her childhood and something she still enjoys watching. Her design is built around the net alone. The top of the net runs at an angle across the coin, its band and knotted mesh in textured relief, and a textured ball crosses above it close to the London 2012 logo, with 50 PENCE beneath the net.

It was one of the 30 coins in the Olympic set issued in 2011.