▶ This article is part of the Complete Guide to Engagement Rings.
The center diamond of an engagement ring has its quality and price set by the international standard 4Cs. The 4Cs are the initials of Carat (weight), Color, Clarity, and Cut (polish). Here we explain the meanings and how to raise satisfaction within your budget.
Carat | the diamond's weight
1 carat = 0.2g. The larger the number, the bigger it looks and the higher the price. For engagement rings, around 0.2–0.5ct is a commonly chosen range.
Color | closer to colorless rates higher
Graded from D (colorless) to Z (yellowish). D–F are the top class, but G–J still look plenty beautiful to the naked eye. How it looks also changes with the metal color.
Clarity | fewer inclusions
From FL (flawless) to I (included). VS–SI class makes inclusions hard to see with the naked eye — a popular range with a good balance of cost and beauty.
Cut | the most important factor for sparkle
The precision of the polish changes the sparkle dramatically even at the same weight. The top grade is Excellent. If you're unsure how to allocate budget, prioritize Cut first for higher satisfaction.
Tips to raise satisfaction within budget
- Don't compromise on Cut (the foundation of sparkle).
- Set Color to G–H and Clarity to VS–SI so you don't overpay for "invisible differences."
- If you prioritize size, allocate to Carat; if you prioritize sparkle, allocate to Cut and Color.
4C priority summary
| Factor | Recommended guideline | Priority |
|---|---|---|
| Cut (polish) | Very Good–Excellent | ★★★ (top priority) |
| Color | G–H | ★★ |
| Clarity | VS–SI | ★★ |
| Carat (weight) | 0.2–0.5ct | ★ (by taste and budget) |
How each carat looks (guideline)
- 0.2ct: about 3.8mm diameter. Refined and understated.
- 0.3ct: about 4.3mm diameter. A popular standard size.
- 0.5ct: about 5.2mm diameter. Solid presence.
About the grading report
A diamond's 4Cs can be confirmed in a grading report issued by a third-party institution. Because it backs up the quality, checking whether a report exists and its contents is reassuring.
A concrete example of budget allocation
For example, with a diamond budget of 100,000 yen, a popular combination is: no compromise on Cut, Color G, Clarity SI, around 0.3ct. If sparkle is the priority, allocate to Cut and Color; if size is the priority, allocate to Carat.
Common misunderstandings about the 4Cs
- "Bigger = higher value" is not true: at the same carat, a poor cut means inferior sparkle.
- "It must be colorless" is not true: G–H still look plenty beautiful to the naked eye.
- "It must be flawless" is not true: with VS–SI, inclusions are hard to see with the naked eye.
Factors beyond the 4Cs
Besides the 4Cs, fluorescence and the diamond's shape also affect how it looks. If you're curious, compare real stones in store and consult the specialist staff to choose with confidence.
Recommended 4C combinations by budget (example)
- Diamond budget about 70,000 yen: Cut Very Good, Color H, Clarity SI, 0.2–0.3ct
- About 100,000 yen: Cut Excellent, Color G–H, Clarity VS–SI, around 0.3ct
- About 150,000 yen and up: Cut Excellent, Color F–G, Clarity VS, 0.4ct and up
In all cases, prioritizing Cut raises satisfaction.
You can choose the diamond in store. First choose a setting from the engagement ring list, and see the engagement ring price guide for prices. Check the real thing from Store Search.