With a 10 power diamond loupe, a gauge, the proper light and some experience you may be able to approximate the size and quality of diamond studs.
Since larger diamond rings are more rare, the price of carats per gram rises dramatically at an exponential rate. A one carat diamond is worth more than several diamond earrings that measure a carat in total weight.
Since earliest days, it had been possible to cut GIA Certified Diamond only by using other diamond earrings. Todays technology has altered this picture. Inclusions can be drilled with lasers. With the drilling of parallel holes, diamond earrings can be sawn in any direction with lasers.