The Art and Science of Gemology

by Kat Paulick

In short, gemology is the scientific study of gemstones. A gemologist identifies, appraises, and certifies gems. Using grading instruments like microscopes, spectroscopes, and refractometers, a gemologist will analyze a stone and categorize it based on properties such as refraction, luster, crystal structure, inclusions, and hardness.

Gemstone identification relies on various tests, each pinpointing a characteristic of the specimen. For instance, while a stone's color may hint at what it might be, it's not a reliable indicator - more of a stepping stone. A gemologist might then test its refractivity, using a refractometer to measure the degree to which light changes direction when it hits the material. The hardness of a stone is measured by the Mohs hardness scale, which gauges the gem's resistance to scratching. On this scale, a diamond rates a ten, whereas quartz rates a 7, and talc rates a 1.

When gemstone identification, gemologists refer to the four C's of a stone: cut, color, clarity, and carat. Cut refers to the quality of the cut rather than the shape. A well-faceted stone will reflect light much better, resulting in a brilliant, sparkling piece of jewelry.

Color is significant in determining a stone's value. Many gemstones appear naturally in different colors. While most people think that sapphires are blue, there are also pink, orange, purple, green, purple, and yellow sapphires. A yellow sapphire may cost $500 per carat, whereas a rare padparadscha sapphire (a pinkish-orange color) can cost up to $15,000 per carat. Saturation, or richness of color, also contributes to valuing gems.

Diamonds naturally range in color from completely clear to light yellow. The color is measured by an alphabetic scale ranging from D (colorless) to Z (yellow), though most diamonds sold fall within the D-J range. Interestingly, a diamond's yellowish color can be hidden by the cut's shape, with a brilliant round diamond hiding color that is the best or the color of the metal. Clarity refers to natural inclusions within the stone, and carat refers to its weight. These factors are all critical in identifying value and working with a gemstone.

Despite humanity's age-old fascination with gemstones, the formal study of gemology is a relatively new science. Education for gemologists and jewelers began in the 1800s, gradually advancing and establishing certifications. A gemological committee was established in the early 1900s by the National Association of Goldsmiths of Great Britain, which evolved into the Gemological Association of Great Britain. They created an accrediting program for gemologists and continue to teach courses, but today's foremost gemstone authority is the Gemological Institute of America.

GIA Headquarters - Carlsbad, CA. Image: GIA

Established in 1931, the GIA was the birthplace of the world's most commonly used diamond grading systems, including the four C's and the alphabetic color scale. It also offers one of the most prestigious credentials in the industry with its Graduate Gemologist program and is the leading source of gemological knowledge and standards. GIA's laboratories are renowned worldwide for their rigorous gemological testing and certification standards. Their grading reports are considered industry benchmarks, providing detailed assessments of gemstone quality based on criteria like color, clarity, cut, and carat weight.

Gemology has, by necessity, expanded along with the jewelry trade. With the advancement and prevalence of synthetic jewels, the need for gemologists who can identify the structure of a specimen and appraise its worth has also increased. Gemology is unique in that it's interwoven with the world of jewelry - giving it the quality of being an art and a science. Because of this, a gemologist's career may involve anything from lab analysis and appraisal to jewelry designing and many things in between.

George Kunz. Image: Wikipedia

Famous self-taught mineralogist George Fredrick Kunz turned a passion for gemstones into a vice-presidency of Tiffany & Co. During his illustrious career, he discovered new gem varieties such as Morganite and Kunzite, worked as a curator for New York City's Museum of Natural History, and published hundreds of articles.

Gemology combines the beauty and intrigue of gemstone artistry with the fascination of ancient geological history. Studying gemstones reveals secrets about our planet, cultures, and ourselves and deepens our understanding of the world.