Method and apparatus for sorting stones

A method of sorting stones within a supply reservoir by viewing said stones individually through a microscope comprising the steps of:

• placing one end of a pick-up tube at a first position disposed at a transfer location whereat said one end is exposed to the stones within said supply reservoir, said pick-up tube having a first opening disposed at said one end, said first opening adapted to form a substantially airtight seal with one of said stones,
• applying a source of vacuum to a second opening disposed at the other end of said pick-up tube, said second opening being in communication with said first opening, whereby a sample stone is held adjacent said first opening,
• moving the one end of said pick-up tube from said first position to a second position outside said supply reservoir whereat said one end is positioned exactly within the field of view of an objective of said microscope such that said sample stone is disposed precisely at the focal length of said microscope objective,
• determining whether said sample stone is to be rejected or accepted by visually observing the sample stone through said microscope when the one end of said pick-up tube is disposed at said second position,
• replacing said supply reservoir at said transfer location with either a reject reservoir or an accept reservoir depending, respectively, upon whether said sample stone is to be rejected or accepted, returning the one end of said pick-up tube to said first position, and
• removing said source of vacuum in order to release said sample stone from said first opening, whereby the sample stone is deposited in the reservoir positioned at said transfer location.