All of the stones in this section exhibit, among other techniques, a kind of carving invented by this artist, which he calls "ultra-intaglio", but which is most commonly called "inside carving." In this process, three-dimensional voids are cut out of the inside of the stone, appearing from outside as sculptural forms. This technique was made practical with the development of diamond carving bits, some of which are represented in the background to this page. Since the appearance of this technique in the early eighties of the last century, a number of other craft artists have taken it up, and it has been copied in the workshops of China.

         Most of the stones currently in this list are quartz crystals, a few are colorless topaz, and one is an aquamarine.

         The quartzes with natural inclusions are from a mine in the Minas Gerais district that was worked in the early part of the Twentieth Century for "optical quartz," material so clear that it could be used for grinding lenses. Crystals with inclusions were discarded into the tailings piles, and decades ago the mine was closed and sold. The buyers, looking through the tailings, found that the discarded, included crystals were quite beautiful, the inclusions coming in many brilliant colors. The tailing piles have now been completely examined, and there are no more of these crystals coming onto the market.