The 4 Cs of Diamonds: Cut, Color, Clarity & Carat Explained

When you buy a diamond – whether as an engagement ring, stud earrings, or a pendant – you will encounter the 4 Cs: Cut, Color, Clarity, and Carat Weight. These four criteria together determine a diamond's quality and price. This guide explains each C in an understandable way and shows what you really need to look for when making a purchase.

C 1: Cut – The Most Important C

The cut is the only one of the 4 Cs that is determined by humans – all others are natural properties. A good cut brings out optimal sparkle; a poor cut makes even a high-quality stone appear dull.

GIA Cut Grades (from top to bottom):

• Excellent: Maximum light performance, the highest quality level
• Very Good: Hardly distinguishable from Excellent, 20–30% cheaper
• Good: Good sparkle, visible compromises – good value for money
• Fair / Poor: Loss of light due to proportions that are too shallow or too deep – avoid

Recommendation: At least Very Good for engagement rings. For everyday jewelry, Good is perfectly adequate.

Popular Diamond Cut Shapes

• Round (Brilliant): 58 facets, maximum sparkle – 75% of all diamonds worldwide
• Oval: Similarly sparkling to round, appears larger on the finger and elongates
• Cushion: Soft corners, romantic, lots of fire
• Emerald Cut: Less glitter, but maximum clarity and elegance
• Pear: Unique, elongates the finger, modern and daring
• Marquise: Boat shape, appears very large visually, very dramatic

C 2: Color – Less Color = More Value

The GIA color scale ranges from D (absolutely colorless) to Z (visibly yellowish). For most buyers, the distinction between D and G is practically impossible with the naked eye – but the price difference is significant.

• D–F (Colorless): Absolutely colorless – highest and most expensive category
• G–J (Near Colorless): Minimal color, not discernible to the untrained eye – best value for money
• K–M (Faint Yellow): Slightly yellowish visible – significantly cheaper, acceptable for yellow gold settings

Recommendation: G–H for white gold and platinum. K–L for yellow gold settings, as the warm metal conceals yellowish stones.

C 3: Clarity – Natural Inclusions

Natural diamonds have inclusions (internal characteristics) and blemishes (surface characteristics) – formed during their creation deep within the earth. The fewer inclusions, the higher the value.

• FL/IF (Flawless/Internally Flawless): No visible inclusions under 10x magnification – extremely rare, extremely expensive
• VVS1/VVS2: Very difficult to see under 10x – for experts and investors
• VS1/VS2: Inclusions visible under a loupe, not with the naked eye – the sweet spot for jewelry
• SI1/SI2: Inclusions sometimes visible with the naked eye, depending on position – great price advantage with good selection
• I1/I2/I3: Clearly visible inclusions – only for a very budget-conscious buyer

Recommendation: VS2 or SI1 for the best price-quality ratio. The human eye sees no difference from FL.

C 4: Carat (Carat Weight) – Size is Relative

1 carat = 0.2 grams. Larger diamonds are exponentially more expensive – not linearly. A 1.0-ct stone often costs 4–5× more than a 0.5-ct stone of the same quality, because large stones are rare.

Pro Tip: A 0.90-ct diamond is almost indistinguishable visually from a 1.0-ct – but costs 15–20% less. Buy just under the "magic sizes" (0.90 instead of 1.0; 0.45 instead of 0.5) for maximum savings with minimal visual compromise.

The Right Priority of the 4 Cs

If the budget is limited, the following order of priority applies: Cut first (never compromise on cut), then color (G–H is sufficient), then clarity (VS2–SI1 is good), then carat (better a little smaller than sacrificing quality).

Zirconia as a 4-C-Free Alternative

For fashion jewelry like at Corelune Jewellery, we use high-quality zirconia stones that are visually appealing – without the complexity and expense of real diamonds.

👉 Discover sparkling jewelry – brilliant for every day!