Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) is an important technique for quantitative chemical analysis. The authors have applied this minimally destructive technique to gemology to take advantage of its high spatial resolution, rapid and direct analysis of gemstones (whether loose or mounted), and precise measurement of a wide range of elements—even in ultra-trace amounts. This article summarizes LA-ICP-MS principles and describes the successful application of this technique to detecting beryllium diffusion treatment in corundum and identifying the geographic origin of emeralds. LA-ICP-MS is significantly less expensive than SIMS and more sensitive than LIBS, which is the least costly of the three instruments.