he well-known 4C standard for diamonds is no secret, but do you really know what it refers to? Several of my customers have mentioned that they don't know how to evaluate the quality of the diamond products they get from their carefully selected suppliers. So, let me walk you through it.
Carats
Carat is a unit of weight specifically used for diamonds. The larger the carat weight, the greater the value of the diamond. Diamonds under 1 carat are considered small and typically do not retain value.
Prices for diamonds of different carat weights
|
Carat Weight |
Price Range (per carat) |
Description |
|
0.25 Carat |
$500 - $1,500 |
Small diamonds, often used for solitaire rings or earrings. |
|
0.5 Carat |
$1,500 - $4,000 |
Medium-small diamonds, suitable for small rings, high cost-performance ratio. |
|
1 Carat |
$4,000 - $10,000 |
Standard-sized diamonds, the most popular, commonly found in engagement rings. |
|
1.5 Carats |
$6,000 - $20,000 |
Larger diamonds, prices vary greatly depending on quality. |
|
2 Carats |
$10,000 - $40,000 |
Classic large diamonds, gradually entering the high-end market. |
|
3 Carats |
$20,000 - $75,000 |
Large diamonds, often used in high-end jewelry and luxury products. |
|
5 Carats |
$40,000 - $150,000 |
Extremely rare and luxurious, prices fluctuate greatly. |
|
10 Carats |
$100,000 - $500,000 |
Super-large diamonds, suitable for collectors or the luxury jewelry market. |
|
20+ Carats |
$500,000 - millions |
Top-tier diamonds, prices can exceed millions of dollars, extremely rare and luxurious. |
Famous large-carat diamonds in the world
- Cullinan Diamond
Estimated Value: The Cullinan Diamond is a historical artifact and a royal gemstone, with an estimated market value of $200-400 million for Cullinan I. The total value of the Cullinan Diamond, considering its historical significance, cultural heritage, and original weight, may approach $1-2 billion.
- Tiffany Yellow Diamond
Estimated Value: As one of the world's most famous yellow diamonds, its market value is extremely high. According to auction records and market demand, its value is approximately $30-50 million.
- The Graff Pink
Estimated Value: Known for its exceptional quality and rare color, this pink diamond set a record in auction history. It sold for $46 million in 2010, with an estimated value of $45-50 million.
- Hope Diamond
Estimated Value: The Hope Diamond is considered priceless due to its rarity as a blue diamond and its deep historical and cultural significance. Its market value is estimated at $200-300 million.
- The Red Emperor
Estimated Value: Extremely rare, belonging to the highly precious category of red diamonds. Similar red diamonds have reached $20-50 million at auction, and The Red Emperor is estimated to be worth $20-60 million.
Clarity
The clarity of a diamond is classified based on international standards, primarily rated by the Gemological Institute of America (GIA). The GIA uses clarity grades based on inclusions (internal flaws) and blemishes (external flaws), taking into account their size, number, position, and visibility.
Prices for diamonds of different clarity levels
|
Clarity Grade |
Definition |
1-Carat Reference Price |
Price |
|
FL |
Flawless, no visible inclusions or blemishes, even under 10x magnification. |
$20,000 - $30,000 |
Extremely rare and highly collectible, the most expensive on the market. Ideal for high-end jewelry, custom pieces, or investments. |
|
IF |
Internally flawless, no internal inclusions, may have minor external blemishes removable by polishing. |
$15,000 - $25,000 |
Slightly less expensive than FL due to external blemishes. |
|
VVS1 |
Very, very slight inclusions, difficult to detect even under 10x magnification. Smaller inclusions than VVS2. |
$10,000 - $20,000 |
Very rare, highly valued, slightly less expensive than FL and IF grades. |
|
VVS2 |
As described above |
$8,000 - $18,000 |
As described above |
|
VS1 |
Very slight inclusions, difficult to detect under 10x magnification. Fewer or smaller inclusions than VS2. |
$6,000 - $12,000 |
Less expensive than VVS grades but still highly valuable. Ideal for most consumers. |
|
VS2 |
As described above |
$5,000 - $10,000 |
As described above |
|
SI1 |
Slight inclusions, more noticeable under 10x magnification. May affect appearance but can still maintain good looks if inclusions are well-positioned. |
$4,000 - $8,000 |
More common, affordable, and suitable for budget-conscious consumers. |
|
SI2 |
As described above |
$3,500 - $7,000 |
As described above |
|
I1 |
Obvious inclusions, visible to the naked eye, potentially affecting transparency, luster, and structural stability. I2/I3 are lower quality than I1. |
$2,500 - $6,000 |
Inclusions affect appearance and stability, lowest price. Suitable for tight budgets but not ideal for long-term investment. |
|
I2/I3 |
As described above |
$1,500 - $4,000 |
As described above |
Note: Prices are for 1-carat diamonds. Actual prices may vary depending on other factors like color, cut, and carat weight.
Color
According to GIA classification standards, diamond colors are divided into white diamonds (colorless) and colored diamonds.
White Diamonds
White diamonds are further categorized from D to Z, reflecting the shift in color from completely colorless to a noticeable yellow or brown tint under white light.
|
Color Grade |
Color Definition |
Price Impact |
|
D |
Completely colorless, the highest grade, extremely rare. |
Market price is the highest, about 20%-30% more expensive than E and F grades. Perfect for those seeking the best quality. |
|
E |
Almost colorless, with a very slight tint detectable only by experts. |
Slightly less expensive than D grade, about 15%-20% lower in price. Still considered high-end. |
|
F |
Near colorless, with a faint tint visible only under specialized equipment. |
Great value, cheaper than D and E grades. Ideal for consumers with slightly lower budgets seeking high quality. |
|
G |
Nearly colorless, with a very faint yellow tint that is hard to notice with the naked eye. |
Excellent value, in high demand, and about 10%-15% cheaper than F grade. |
|
H |
Nearly colorless, but with a slight yellow tint visible in certain lighting. |
Still considered high-quality but about 10%-15% cheaper than G grade. Suitable for budget-conscious buyers. |
|
I |
Close to colorless, but with a more noticeable yellow tint to the naked eye. |
Around 15%-20% cheaper than H grade, good for those prioritizing cost-effectiveness. |
|
J |
Close to colorless, but the yellow tint is more prominent, especially in white gold or platinum settings. |
20%-25% cheaper than I grade, often used in budget-friendly rings or daily jewelry. |
|
K-M |
Light yellow, with the yellow or brownish tint easily visible to the naked eye. |
30%-40% cheaper than J grade, often used for larger diamonds or paired with warm-tone metals like rose gold or yellow gold. |
|
N-Z |
Light to prominent yellow or brown tint, highly noticeable to the naked eye. |
The most affordable, over 50% cheaper than colorless diamonds. Commonly used in labs, educational purposes, or for consumers with very tight budgets. |
Colored Diamonds
Only one in every 1,000 diamonds is naturally colored. The deeper and more vibrant the color, the higher the price. Additionally, larger carat weights make the color even more noticeable and valuable.
|
Color |
Rarity |
Price Range (per carat) |
|
Yellow |
Fairly common, more vibrant shades (e.g., canary yellow) are especially rare. |
$5,000 - $15,000 |
|
Brown |
The most common fancy color, widely marketed as “champagne diamonds” or “chocolate diamonds.” |
$2,000 - $8,000 |
|
Pink |
Rare, with deep pink diamonds being extremely valuable, mostly sourced from Argyle Mine in Australia. |
$100,000 - millions |
|
Blue |
Extremely rare, formed by boron impurities, with deep blue being the most valuable. |
$200,000 - millions |
|
Green |
Rare, usually caused by natural radiation, with deep green being especially valuable. |
$50,000 - millions |
|
Orange |
Rare, caused by nitrogen impurities, with deep orange being particularly prized. |
$50,000 - $200,000 |
|
Red |
The rarest of all diamond colors, with pure red diamonds being nearly nonexistent. |
$1,000,000 - millions |
|
Purple |
Extremely rare, with lighter purple diamonds being more common. |
$100,000 - $500,000 |
|
Black |
Opaque, formed by large amounts of graphite or inclusions. Stylish and unique. |
$1,500 - $10,000 |
World-Famous Colored Diamonds
Apart from the large-carat colored diamonds mentioned earlier, other world-famous colored diamonds include:
- Brown Damonds
- Pink Diamonds
- Green Diamonds
- Orange Diamonds
- Red Diamonds
- Purple Diamonds
A representative purple diamond is the “Royal Purple Diamond”, weighing 7.34 carats. It caused a sensation at an auction in 2017 due to its deep purple color and exquisite cut.
- Black Diamonds
Cut
Diamonds have a high refractive index and dispersion rate (around 0.044), allowing them to break white light into various colors. A well-designed cut takes advantage of this to create the rainbow-like fire and brilliance diamonds are famous for. Different cuts have varying levels of difficulty and material loss, which affect their prices.
Major diamond cuts, features, and price impacts
|
Cut Type |
Features |
Price Impact |
|
Round Brilliant Cut |
The most classic and popular cut, accounting for over 70% of the diamond market. It has 58 facets and maximizes fire and brilliance. |
Due to high material loss and cutting difficulty, its per-carat price is 20%-40% higher than other cuts. |
|
Princess Cut |
Square or rectangular, sharp corners, with a modern look. Its brilliance radiates from the center to the four corners. |
Less material loss, about 20%-30% cheaper than round cuts. |
|
Cushion Cut |
Rounded square or rectangular cut, combining vintage and modern styles with a softer glow. Its fire is similar to round cuts, making it very popular. |
Less material loss, about 10%-20% cheaper than round cuts. |
|
Oval Cut |
Elegant and elongated, visually enhancing the perceived carat weight. Ideal for those with long fingers. |
About 10%-15% cheaper than round cuts, but rising in demand. |
|
Pear Cut |
A combination of round and oval shapes, resembling a teardrop. Unique and romantic, it visually elongates the fingers. |
About 15%-25% cheaper than round cuts, though high-quality stones may cost more due to cutting loss. |
|
Emerald Cut |
Rectangular step-cut with a large table, showcasing the diamond's transparency and noble elegance. Focuses more on clarity than brilliance. |
About 20%-30% cheaper than round cuts, though high-clarity diamonds may be pricier. |
|
Radiant Cut |
Square or rectangular, similar to emerald cuts but with more facets, combining fire and transparency. |
About 10%-20% cheaper than round cuts. Diamonds with high symmetry are more expensive. |
|
Marquise Cut |
A long, narrow oval shape with sharp ends, making the diamond appear larger than its actual weight. Perfect for those with slender fingers. |
About 10%-20% cheaper than round cuts, though precision-cut diamonds are pricier. |
|
Heart Cut |
A romantic heart shape with highly complex cutting requirements, perfect for special occasions or emotional expressions. |
About 10% cheaper than round cuts, though well-cut diamonds are still expensive. |
|
Trilliant Cut |
A triangular shape with sharp edges, bright fire, often used as side stones to complement the center stone. Bold and unique. |
About 25%-35% cheaper than round cuts, rarely used as the center stone. |
|
Asscher Cut |
Square step-cut, similar to the emerald cut but with more balanced proportions, creating a unique "kaleidoscope" effect. |
About 20%-30% cheaper than round cuts, suitable for high-clarity diamonds. |
Synthetic Diamonds
Synthetic diamonds are nearly indistinguishable from natural ones and are becoming a popular choice in the market. They are typically 1/3 to 1/2 the price of natural diamonds and come with the added benefit of being environmentally friendly. The two main methods for producing synthetic diamonds are High-Pressure High-Temperature (HPHT) and Chemical Vapor Deposition (CVD).
HPHT
This method mimics the natural formation process of diamonds by placing carbon under extremely high temperatures (about 1,500°C) and pressures (5-6 GPa). It has lower production costs, with prices ranging from $800 to $2,000 per carat.
CVD
The CVD process allows for more precise control over the diamond's color and clarity, producing high-quality colorless or specific-colored diamonds. These diamonds are often used in high-end jewelry markets, with prices ranging from $1,000 to $3,000 per carat.
Top Synthetic Diamond Brands
- Features:
Manufactured using CVD technology.
Available in colors like pink, blue, and white.
Transparent pricing, with a fixed price of $800 per carat.
Focuses on modern, affordable jewelry targeting younger consumers.
- Signature Product:
Pink synthetic diamond necklaces, symbolizing sustainable and affordable luxury.
- Features:
Combines advanced cutting techniques with lab-grown diamond production.
Primarily used for wedding rings and high-end fashion jewelry.
- Signature Product:
The Swarovski Created Diamonds Engagement Ring, featuring colorless synthetic diamonds with classic cuts.
- Features:
Manufactured using 100% renewable energy.
Designs focus on simplicity and elegance, catering to modern women.
- Signature Product:
The Brilliance diamond bracelet, combining delicate synthetic diamonds with gold or platinum settings.
- Features:
Minimalist designs combining synthetic diamonds with eco-friendly metals.
Appeals to environmentally conscious luxury consumers.
- Signature Product:
The LUNE ring series, featuring high-clarity, colorless synthetic diamonds in minimalist designs.
Diamond Foundry Haute Couture Jewelry
- Features:
Collaborates with high-end designers to create custom diamond jewelry.
Uses CVD technology to produce diamonds of the same quality as natural ones.
- Signature Product:
The “Architectural Diamond” series, created in collaboration with Dior, showcases modern design aesthetics.
What are the authoritative testing organizations?
You should request an authoritative diamond authenticity certificate from your supplier. Diamonds with the following common certificates are reliable in terms of authenticity:
Summary of Common Diamond Certification Authorities
|
Certificate Name |
Introduction |
Features |
|
Issued by the Gemological Institute of America, the most authoritative gemstone testing organization globally. |
Globally recognized, suitable for high-end natural diamonds, highly reliable testing reports. |
|
|
Issued by the International Gemological Institute, widely used for both natural and lab-grown diamonds. |
Highly authoritative in the synthetic diamond field, suitable for mid-range markets and lab-grown diamonds. |
|
|
Issued by Europe’s diamond authority, headquartered in Antwerp, Belgium. |
Highly recognized in the European market, suitable for high-end natural diamond testing. |
|
|
A U.S.-based independent gemological lab known for fairness and impartiality. |
Provides authenticity guarantees and refund commitments, suitable for high-end consumers and retailers. |
|
|
Issued by the European Gemological Laboratory, specializing in large-carat diamond testing. |
Lower cost but less authoritative in certain markets. |
|
|
Ensures diamonds are not “conflict diamonds,” a global certification standard. |
Focuses on ethical sourcing, suitable for legally compliant diamond trade. |
|
|
Records the complete history of a diamond from mining to sale using blockchain technology. |
An emerging technology that enhances trust in product origin, gradually applied in high-end markets. |
|
|
Issued by the National Gemstone Testing Center of China. |
Highly recognized in the domestic market, suitable for Chinese consumers and local sales. |
Testing Diamonds Yourself
If you are still concerned, you can also choose to have the diamond tested independently. Here’s how you can do it:
Preparation Stage
- Check Existing Documents:
Gather all related documents, including existing diamond certificates (if available), purchase invoices, and transaction records.
If the diamond has a laser inscription number, use a magnifying glass to check for the inscription on the diamond girdle and compare it with the certificate number. - Ensure Safety:
Store the diamond in a secure jewelry box with soft fabric or sponge padding to prevent damage during transport. - Choose a Testing Institution:
Select a reputable institution like GIA, IGI, or NGTC, and avoid small or non-certified organizations.
Contact the institution via their official website or phone to learn about their services and fees, and schedule an appointment. - Record Diamond Appearance:
Take photos of the diamond, including its front, sides, and any visible girdle inscriptions, for reference.
Visit the Testing Institution
- Confirm the Route:
Find the exact address and working hours of the institution. Plan your visit accordingly.
If you cannot visit in person, consider using courier services. Always purchase high-value insurance and use secure packaging. - Bring the Diamond and Documents:
Carry the diamond, relevant certificates, and documents in a single folder for safety.
Bring identification (e.g., ID card or passport) for registration purposes.
At the Testing Institution
- Registration:
Communicate your testing needs to the staff and specify your purpose (e.g., verifying authenticity, confirming 4C standards, checking for treatments).
Fill out a testing application form with the diamond’s basic information (weight, shape, purchase date, etc.) and your personal details. - Pay Testing Fees:
Fees vary depending on the diamond's weight and the testing services requested.
Receive Testing Results
The institution will provide an official report, including details about the diamond’s 4C standards, authenticity (natural or synthetic), and whether it has undergone enhancements or treatments.
Verify Results
- Cross-check the information in the testing report with your original certificate or expectations.
- If you have questions, consult the institution’s staff about any professional terminology or conclusions in the report.
Follow-Up Actions
- If Results Match:
Store the testing report alongside the original documents for future reference. - If Results Don’t Match:
Communicate with the seller immediately, providing the testing report as evidence to request a return, compensation, or reevaluation of the transaction.