Bought this cheapo diamond grit set for £7.50 inc p&p. Some weird sizes like 28 and 30mm. Don't think I've Starretts to match...27 and 32 the nearest maybe. They're similar but lighter construction to the couple (40 & 65mm) I first use to drill the three holes in the tile that goes over the shower valve.   You get:   6mm, 8mm, 10mm, 12mm, 14mm,16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 35mm, 40mm, 45mm, 50mm         Going to t