"I'm thinking about ordering a custom wedding ring or piece of jewelry, but which metal should I choose?"
This is one of the most common questions we hear at Fujimori Tokyo during the initial consultation.
In the world of fine jewelry, the precious metals used to craft rings and other pieces are known as base metals (called jigane in Japanese). Choosing the right metal is one of the most important decisions you'll make, as it affects not only the appearance of your jewelry but also its durability, comfort, and long-term wear.
In Japan, platinum and 18K gold (K18) are the two most popular precious metals for wedding rings and engagement rings. While platinum remains a timeless favorite, 18K gold is available in a variety of beautiful colors, each offering its own unique character and style.
18K, K18, or 750: What's the Difference?
When browsing imported or international jewelry, you may come across stamps such as "18K" or "750." You might wonder how they differ from K18, but they all indicate the same thing: the gold contains 75% pure gold.
The only difference is the labeling convention.
- 750: this follows the international millesimal fineness system, where "750" means the metal is 750 parts pure gold out of 1,000 parts, or 75% pure gold—equivalent to 18-karat gold. This is a millesimal fineness marking commonly used in Europe and other regions, where 750 out of 1,000 parts is pure gold.
- 18K: this notation is commonly seen in overseas jewelry—such as Hawaiian jewelry, as well as pieces from Asia, Europe, and the United States—where the “K” appears after the number (known as “post-karat” marking, e.g., 18K).
- K18: the standard notation commonly used in Japan, where “K” appears before the number (known as “front K”).
At our store in Japan, we use the hallmark “K18”. Compared to 9K (9 karat) and 14K (14 karat) commonly found in Australia and other overseas markets, K18 contains a higher proportion of pure gold. This results in a deeper, richer luster, greater intrinsic value as an asset, and a lower likelihood of causing metal allergies.
⚠️ Important Notice About Our Precious Metal Materials
At our atelier, we do not work with or offer commonly circulated overseas metals such as K14 (14K gold) or K10 (10K gold). For wedding rings and custom jewelry meant to last a lifetime, we carefully prioritize both brilliance and durability. For this reason, we exclusively use K18 (18K gold) for all gold pieces.
We also do not produce items in pure gold (24K gold). While pure gold is highly valuable, it is extremely soft and therefore not suitable for everyday wear rings, as it is more prone to bending and scratches. To ensure a balance between refined craftsmanship and long-term durability, we have chosen to work exclusively with 18K gold.
💍 “Quality Assurance" Engraved Into Every Piece of Jewelry
At Fujimori Tokyo, every gold piece we craft is engraved on the inside with the hallmark “K18” as a guarantee of quality.
This engraving certifies that each piece is made of 18-karat gold—meaning it contains 75% pure gold—and is a mark of our full responsibility for its authenticity and standard of quality. Because it is not visible from the outside, our artisans carefully engrave this hallmark one by one, ensuring that every piece carries a quiet but lasting assurance of craftsmanship and integrity.
Why Does K18 Gold Come in Different Colors?
Yellow gold, rose gold, champagne gold… 18K jewelry comes in several color variations. But if it’s all 18K, why does the color differ?
The answer lies in the composition of the alloy metals used. While 18K consists of 75% pure gold, the remaining 25% is made up of other metals such as copper, silver, and palladium. The specific balance of these metals determines the final color tone of the gold.
100% pure gold is extremely soft, which makes it less suitable for rings worn every day over many years, as well as for delicate craftsmanship. For this reason, other metals are mixed in to improve durability. By adjusting the remaining 25% of the alloy composition, a range of beautiful tones known as “colored gold” can be created.
There are slight differences in hardness and malleability depending on the color, but each piece is carefully handled one by one by our skilled artisans. Unless you have specific concerns such as metal allergies, you are free to choose your preferred gold color.
Rings We’ve Crafted
◆18K Yellow Gold
This is a classic, versatile color that pairs effortlessly with casual outfits. It looks especially beautiful against sun-kissed, healthy tanned skin, as well as warm-toned (yellow undertone) complexions. It also adds a bright, uplifting touch of elegance to an active, on-the-go lifestyle.
◆18K Champagne Gold
This is a refined gold with a beige-like tone that gives an elegant and calm impression. It blends beautifully with the skin, making it a popular choice even for those who are not used to wearing rings in their daily life.
Because of its understated appearance, it is also highly popular among men. It complements all skin tones—whether cool undertones (blue-based) or warm undertones—gently blending in with any complexion.
◆18K Rose Gold
Soft and charming, pink gold gives a gentle and delicate impression. This warm tone also enhances the skin, making it appear brighter, healthier, and more radiant. It is especially flattering on fair skin and cool-toned complexions, where its subtle glow stands out beautifully.
◆Custom-Made “Two-Tone (Multi-Color) Combinations"
One of the unique appeals of made-to-order jewelry is the ability to create a “combo ring” using two different metal colors. This allows you to enjoy a truly one-of-a-kind design that can only be achieved through customization. It also pairs beautifully with your existing jewelry, making it easy to incorporate into a stacking style.
The way a ring’s color appears can vary depending on your skin tone and the overall impression of your hands. We highly recommend trying on different metal colors to find the combination that feels just right for you.
Since the look of each ring can change depending on skin tone, we encourage you to try them on and choose your favorite color in person!
For Customers Living Overseas
Fujimori Tokyo welcomes customers living overseas who design and order rings to coincide with short trips back to Japan, as well as international online orders from around the world.
If you have any questions about sizing (including conversion from international ring sizes to Japanese sizing) or about arranging delivery and pickup within a limited stay, please feel free to contact us anytime via LINE or our inquiry form. We are happy to assist you in both Japanese and English.
