Editor’s Note
Brillar, Japan’s first moissanite-specialized jeweler, has secured a domestic patent for a new moissanite manufacturing method, co-invented by Kyoto University’s Professor Tsunenobu Kimoto and Brillar CEO Isatoshi Ohara. The company is now pursuing international patents in the U.S. and China, supported by JETRO.
Brillar, Japan’s first moissanite-specialized jeweler, has acquired a domestic patent for a moissanite manufacturing method, with Professor Tsunenobu Kimoto from Kyoto University’s Graduate School of Engineering and Brillar’s CEO, Isatoshi Ohara, as co-inventors. The company is also applying for international patents in the United States and China with support from JETRO’s “Support Program for Foreign Patent Applications by SMEs, etc.”
Patent Details:
【Patent Number】Patent No. 6903362
【Title of Invention】Method for Manufacturing Crystals for Synthetic Gemstones
【Patent Holder】Brillar Co., Ltd.
【Inventors】Tsunenobu Kimoto, Isatoshi Ohara
【Registration Date】June 25, 2021 (Reiwa 3)
Moissanite is a silicon carbide (SiC) crystal. While SiC crystals are widely used as semiconductor device materials, the single crystals for this purpose are typically amber-colored and unsuitable for gem use. Therefore, “colorless, transparent, and brilliant SiC crystals” for gemstone purposes have been manufactured using methods like growing seed crystals under specific conditions (prior art).
This patent provides a method to decolorize colored SiC crystals, which are normally unsuitable for gem use, making them usable as synthetic gemstone moissanite.
Applying this invention is expected to yield the following benefits:
1. Enables the production of moissanite at a relatively lower cost compared to mainstream methods by utilizing commercially available SiC single crystal ingots for semiconductor device manufacturing.
2. Allows for the effective utilization (reuse) of “off-spec SiC single crystals”—those that do not meet shape or quality standards during semiconductor device material production.
3. Since the raw materials for synthesizing SiC single crystals for semiconductors and SiC crystals for moissanite are nearly identical, synthesizing moissanite from colored SiC crystals is less likely to hinder the procurement of semiconductor device materials.
The coloration in SiC crystals for semiconductor materials is due to impurities added for reducing electrical resistance. By applying a proprietary treatment to these impurity-containing SiC single crystals, specific defects are created within the crystal. These defect levels capture electrons excited from the impurity levels, eliminating light absorption at 460nm, thereby achieving decolorization.
Founded in 2017 as Japan’s first moissanite-specialized jewelry brand, Brillar has contributed to the spread of moissanite in Japan. Natural gemstones, especially diamonds, face serious issues like environmental damage from mining, human rights problems including child labor, and funding conflicts. Moissanite is an extremely clean and ethical artificial gemstone free from such problems.
The company aims to further contribute to the spread of moissanite by developing a manufacturing method that further reduces time and energy costs compared to existing methods. Brillar also expects its existing connections with major semiconductor manufacturers to be a significant driving force in refining the developed technology from research results to practical application.
Currently, Brillar carefully selects moissanite rough stones (loose stones) manufactured overseas and has them processed into jewelry by contracted workshops. However, engaging in in-house rough stone manufacturing is expected to enable more stable provision of moissanite jewelry.
Moissanite is known as silicon carbide (SiC) in the electronics field—a groundbreaking semiconductor called the ‘ace in the hole for energy saving’ in areas like computer power supplies, inverter appliances, and motor control for electric vehicles and trains. It is academically and industrially very interesting that the high-purity crystal of this semiconductor holds high value as a gemstone.
If moissanite’s recognition increases further, it can attract more people to silicon carbide, drawing broader societal attention to the material. Moreover, while moissanite’s manufacturing energy is already environmentally friendly at less than 1/100th that of lab-grown diamonds, this research enables the reuse of materials like SiC crystals unsuitable for semiconductors—which would otherwise be waste—into gemstones, contributing further to SDGs.”
– Professor Tsunenobu Kimoto, Graduate School of Engineering, Kyoto University
Moissanite is a gemstone of SiC crystal. The colorless, transparent, and sparkling moissanite is a natural material discovered in a meteorite in 1893. It possesses what is said to be the world’s highest brilliance—2.5 times that of a diamond—and high durability. While very similar to diamond, it features superior properties in areas like impact resistance (toughness) and resistance to clouding (low oil affinity).
Natural moissanite is highly rare and scarcely available on the market. An American company succeeded in manufacturing it and began selling artificial moissanite in 1998. The manufacturing patent obtained at that time expired in the US in 2015, and subsequently in various countries worldwide. Currently, high-quality artificial moissanite is produced in countries like the US and China. It is already widely accepted by consumers in the US and supported as an option for engagement rings.
In Japan, attention to ethical jewelry materials like lab-grown diamonds and fair-mined gold has been growing among jewelry suppliers and consumers in recent years, considering price and traceability. Similarly, moissanite is gaining increasing attention year by year for its ethical aspects (free from mining-related issues), excellent material properties, and high cost-performance, leading to a rise in consumers and new handling brands in Japan.
