The production of polychrome sculptures in Brazil during the 18th and 19th centuries was very important. The blood of some Brazilian Christ sculptures was represented with red pigments, red lakes or both, but the drop of the blood was a shiny and transparent red material, known as ruby. In popular tradition and the descriptions of art magazines, these drops are called ruby or red resin. Samples of ten Baroque and Rococo Christs (nine sculptures and one painting) from the museums and churches of Minas Gerais were examined with a scanning electron microscope equipped with an X-ray energy dispersive spectrometer (SEM-EDS). Scientific methodology confirmed the use of orpiment, the yellow sulfide of arsenic (As2S3), based on the description of an ancient recipe in a Portuguese manual. This paper also discusses the fabrication of the rubies, contributing to the knowledge of our cultural heritage. -- SCMRE