Gemstone Grading & Properties
Are Gemstones Graded?
Yes, gemstones are graded, but unlike diamonds—which follow a strict 4Cs grading system (Cut, Color, Clarity, Carat)—gemstones are evaluated using a more flexible and subjective grading approach. The grading system for gemstones focuses primarily on color, clarity, cut, and carat weight, but the standards vary depending on the type of gemstone.
How are Gemstones Graded?
Gemstones are graded, but unlike diamonds—which follow a strict 4Cs grading system (Cut, Color, Clarity, Carat)—gemstones are evaluated using a more flexible and subjective grading approach. The grading system for gemstones focuses primarily on color, clarity, cut, and carat weight, but the standards vary depending on the type of gemstone.
Color
Hue: The dominant color of the gemstone (e.g., blue for sapphire, green for emerald).
Tone: Refers to how light or dark the color appears. Ideal tones are typically medium to medium-dark.
Saturation: Refers to the intensity or vividness of the color. Highly saturated colors are more valuable and desirable.
Color slightly detectable when compared to diamonds of better grades, a good value.
Pro Tip:
- Rich, vibrant colors are often more valuable than overly light or dark tones.
Clarity refers to the presence of inclusions (internal flaws) and blemishes (external imperfections). Unlike diamonds, some inclusions in colored gemstones are acceptable, as they can indicate the stone's natural origin. Clarity grades are typically described as:
Eye-Clean: No visible inclusions to the naked eye (highly desirable).
Slightly Included: Some visible inclusions that don’t affect brilliance.
Heavily Included: Visible inclusions that may impact the stone’s durability.
For gemstones like emeralds, inclusions (called "jardin") are expected and do not necessarily reduce the value as much as they would in diamonds.
Slightly included 2. Inclusions are visible under 10x magnification and may be visible with unaided eye. More inclusions than SI1.
Cut The cut of a gemstone enhances its brilliance, color, and shape. A well-cut gemstone reflects light beautifully and showcases its best features. Unlike diamonds, where cut is precisely defined, gemstone cuts prioritize maximizing color and minimizing inclusions. Popular cuts include:
Oval, Cushion, and Round: Maximizes brilliance and sparkle.
Emerald Cut: Highlights color while minimizing stress on the stone.
Cut to the most exacting standards. These diamonds have the most desirable dimensions and are proportioned to return the maximum possible light.
Carat Weight Carat measures the weight of the gemstone, not necessarily its size. Larger gemstones are rarer and often more valuable, but color and clarity can have a greater impact on a gemstone’s price than carat weight.
Shown with 1.0ct
Grading Systems for Popular Gemstones:
Sapphires and Rubies: Often graded based on color intensity, clarity, and cut. Unheated, untreated stones with vibrant color and few inclusions are the most valuable
Emeralds: Graded with a focus on color and clarity, as natural inclusions are common. Vivid green with minimal inclusions is the most prized.
Aquamarines: Valued primarily for color and clarity, with pure, vibrant blue stones being the most desirable.
Pro Tip:
- When purchasing a colored gemstone, ask for a certification from a trusted gemological lab, such as the GIA (Gemological Institute of America) or AGL (American Gemological Laboratories), to verify authenticity, treatment, and grading.
Gemstone Properties
| Gemstone | Hardness (Mohs Scale) | Color Range | Clarity | Preferred Cut |
|---|---|---|---|---|
| Diamond | 10 | Colorless (most common), also available in fancy colors like yellow, blue, pink, and green | Ranges from flawless to included; high clarity prized in colorless diamonds | Round brilliant (most popular), but also oval, emerald, cushion, and pear for variety |
| Sapphire | 9 | Blue (most popular), but also pink, yellow, green, purple, and white | Generally eye-clean, but inclusions are acceptable in some fancy colors | Oval, round, cushion, and emerald cuts maximize brilliance |
| Emerald | 7.5 – 8 | Vibrant green to bluish-green | Often has visible inclusions ("jardin"), which are acceptable due to rarity | Emerald cut (step cut) to highlight color and reduce pressure |
| Ruby | 9 | Rich red, with shades from pinkish-red to deep crimson | Typically has visible inclusions, considered acceptable in high-quality rubies | Oval, cushion, and round cuts enhance color and brilliance |
| Aquamarine | 7.5 – 8 | Pale blue to greenish-blue | Usually eye-clean, with minimal inclusions | Emerald, oval, and pear cuts emphasize its clarity and color |
Pro Tips:
- When choosing a gemstone, consider both hardness and clarity for durability, especially if the stone will be worn daily.
- Sapphires and rubies are great choices for engagement rings, while emeralds and aquamarines offer a vibrant, softer look that requires a little extra care.
