The RHG181 Diamond Tester is a portable gem tester designed for jewelry professionals in the United States. With a compact size of 8.66 x 4.33 x 3.15 inches and a weight of 1.3 pounds, this refractometer is ideal for testing diamond and gemstone quality. Its advanced technology allows for accurate readings of the refractive index, ensuring the authenticity and value of jewelry pieces. This tool is essential for jewelry care, design, and repair, making it a valuable addition to any professional's toolkit.