Size: 4mm (84 - 95 beads)
         6mm (63 - 58 beads)
         8mm (47 - 543 beads)
         10mm (38 - 36 beads)
         12mm (30 - 31 beads)

Beads hole size:
4mm round beads hole size - approx 0.6mm
6mm round beads hole size - approx 0.8mm - 1mm
8mm round beads hole size - approx 1mm
10mm round beads hole size - approx 1mm - 1.2mm
12mm round beads hole size - approx 1mm - 1.5mm

Beads sizes and color do vary between different gemstones or even batches for the same gemstone. 
Please note that there could be a variation of up to 1mm - 1.5mm in size.