Telling a good diamond typically involves evaluating its quality based on standard criteria known as the 4 Cs: Cut, Colour, Clarity, and Carat Weight. These factors collectively determine a diamond's beauty, brilliance, and value.
The 4 Cs of Diamond Quality
Understanding the 4 Cs is the key to assessing a diamond's quality. Here's a breakdown:
Colour
A diamond's colour refers to its lack of colour. The Gemological Institute of America (GIA) grades colour on a scale from D (colourless) to Z (light yellow or brown).
- Optimal Brilliance: Ideally, you want a diamond that falls within the "near colorless" range (D-F) for optimal brilliance, as these diamonds show virtually no colour visible to the naked eye.
- Diamonds in the G-J range are still considered "near colorless" and can appear colourless when mounted, offering excellent value.
- Colours K-Z show increasingly noticeable yellow or brown tints.
Clarity
Clarity refers to the presence or absence of inclusions (internal flaws) and blemishes (surface imperfections).
- Natural Imperfections: Diamonds are natural materials and may have internal flaws (inclusions) or surface blemishes.
- Impact on Brilliance and Value: These imperfections can affect the diamond's brilliance and value. Fewer and smaller imperfections result in higher clarity and typically higher value.
- Clarity is graded on a scale from Flawless (FL) to Included (I3).
- Flawless (FL): No inclusions or blemishes visible under 10x magnification.
- Internally Flawless (IF): No inclusions visible under 10x magnification.
- Very, Very Slightly Included (VVS1 and VVS2): Inclusions are extremely difficult to see under 10x magnification.
- Very Slightly Included (VS1 and VS2): Inclusions are difficult to see under 10x magnification.
- Slightly Included (SI1 and SI2): Inclusions are noticeable under 10x magnification.
- Included (I1, I2, and I3): Inclusions are obvious under 10x magnification and may be visible to the naked eye, potentially affecting brilliance and transparency.
Cut
Often considered the most important C for a diamond's beauty, cut refers to how well a diamond's facets interact with light. It's not about the shape (like round or princess) but the proportions, symmetry, and polish.
- A well-cut diamond reflects and refracts light to maximize brilliance (white light reflection), fire (colour flashes), and scintillation (sparkle).
- Poorly cut diamonds can appear dull and lifeless, regardless of their colour or clarity.
- Cut grades are typically Excellent, Very Good, Good, Fair, and Poor.
Carat Weight
Carat weight is the standard unit for weighing diamonds. One carat is equivalent to 200 milligrams.
- Carat weight measures a diamond's size, but two diamonds of the same carat weight can differ significantly in value based on their cut, colour, and clarity.
- Larger diamonds are rarer and therefore generally more valuable, assuming other factors are equal.
Summary Table: The 4 Cs
| Aspect | What it is | How it affects quality | Key Points (as per reference/standard) |
|---|---|---|---|
| Cut | Proportions, symmetry, and polish | Maximizes brilliance, fire, and sparkle | Graded Excellent to Poor; crucial for light performance. |
| Colour | Lack of colour (or presence of colour) | Affects brilliance (especially in near-colourless range) | Graded D-Z; D-F range is ideal for optimal brilliance. |
| Clarity | Presence of inclusions (internal) / blemishes (surface) | Affects brilliance and value | Graded FL-I3; Imperfections affect brilliance and value. Fewer/smaller imperfections mean higher clarity. |
| Carat Weight | Diamond's weight (size) | Affects rarity and value | Larger carat weight generally means higher value, assuming other 3 Cs are equal. |
By assessing these four characteristics, you can determine the quality and ultimately the "goodness" of a diamond.
