Measurement of rough gemstones

A measurement system 100 is used to make optical and weight measurements of a rough gem stone. A feed system such as a vibrating bowl 110 delivers the stone to an optical measurement location where a 3D model of the stone is generated by imaging assembly 170 and is then conveyed to a second measurement location where it is weighed. The stone may be positioned in the imaging assembly 170 by retractable stabilising elements 150, 155 and then held in place by a vacuum 176 and rotated for multiple images. The weighing assembly may include a weigh cell 140 and a weigh pan 190 enclosable by a flap. There may be a double feed detection assembly 120, 125 to ensure only a single stone is passing through the system at a time, and an upper hold gate 130 to eject stones from the feed when more than one stone is present.