Quantity: 24 materials. they were picked randomly, no one knows which ones you will get till you open the parcel :). Cabochon Diameter: 20mm (0.79 inch), Cabochon Thickess: 5mm to 6mm Please note you will not receive all cabochons in picture, we ship 24pcs randomly but no duplicated, but if you buy 2 lots, you may get a lot of same materials Not all of them from same supplier, so thickness is varies.Well polished, sized, shaped, flat on backside, good for setting Please note there's no chart will come in parcel,you may compare with the 2nd picture in listing after you get the stones. Do not hesitate to contact us if you are still not sure what you got. If any of them you got is defective or broken in transit, pls contact us for a partial refund or replacement.