The word “calibrated” refers to small gemstones that match in shape, size, and beauty. As can be seen in many of the pieces of jewelry in this book, the number of calibrated stones in a single piece can range from several to more than twenty. The beauty they shows is different from that of large gemstones, and their price performance is excellent.

It can be said that the production of calibrated stones first became possible in the 20th century. Prior to that, the technical skills required to precisely cut small gemstones were not sufficient. Furthermore, mining production could not secure the quantities needed to match shape, size, and beauty. The diamond production of 100 years ago was only 1/60 of current levels.

The photograph to the right shows five different gemstones cut into 2.2-millimeter square shapes. Ruby, sapphire, emerald, and diamond are gemstones with long traditions, but tsavorite arrived on the market in the 1960s. Considering that only a few of the many gemstones types show distinct color with high levels of transparency and beauty in such small sizes, the highly valuable nature of savorite becomes apparent. The princess cut first appeared in the 1970s. this cut is used not only with diamonds, but also with rubies, sapphires, emeralds, and tsavorites, and it shines with a strongly brilliant beauty that is not seen in step cuts.

Matching quality in small stones is difficult. Gemstones are polished from rough material that differs in shape, transparency, color, and imperfections, resulting in individual differences in quality. They are unlike the uniform synthetic stones that are manufactured in chemical factories. In addition, to adjust the tone of color or to minimize weight loss, gemstones may be cut to slightly thin or thick depths that do not have the desired balance. Because gemstones are rare products of nature with unique characteristics, cutting them within specified ranges is not an easy task.

Gemstones are individually matched when making jewelry, taking into consideration the margin of error allowable for construction and stone setting.