Screen Calipers
The Screen Calipers can be used with any program where fast and accurate measurements are required. Manipulating the application is simply accomplished through use of the mouse, and a variety of keyboard controls allow for extra fine alignment. Originally created for graphics and web... To aid measurement the Caliper's mouse pointers will change making alignment intuitive and simple. ... By pressing Ctrl, Shift and Alt while dragging with the mouse the Calipers will extend, rotate or snap to 90 degrees.
http://www.iconico.com/caliper/Calipers.zip - 907Kb - Download - Screenshot

GemTracker Pro
Gem stones processing management software. Keeps track of your memos, repairs, recuts, roughs and purchases from start to finish. Maintains a Administrator defined custom gem inventory database over searching, sorting and editing your gem inventory. Includes a built in image viewer with the... Features include Invetory, Customer database, reports summary of multiple reports Gem Processing. ... A dream come true for gem professionals, rock hounds, collectors, hunters, gemologists, hobbiest, enthusiests, Cutters, Gem Dealers, importers, wholesalers and retailers.
http://www.goldcalculator.com/files/gemtracd.exe - 14Mb - Download - Screenshot

Screen Calipers Mac Edition
The Screen Calipers can be used with any program where fast and accurate measurements are required. Manipulating the application is simply accomplished through use of the mouse, and a variety of keyboard controls allow for extra fine alignment. Originally created for graphics and web... To aid measurement the Caliper's mouse pointers will change making alignment intuitive and simple. ... By pressing Ctrl, Shift and Alt while dragging with the mouse the Calipers will extend, rotate or snap to 90 degrees.
http://www.iconico.com/caliper/MacCalipers.zip - 396Kb - Download - Screenshot