Diamond Sparkles of
your Love

About our Diamonds Let the Diamond Brighten the Future of Two

Just as each person is unique,
natural diamonds, being minerals,
also possess individual characteristics.

To illuminate and enhance
the story of the couple getting married,

ith values the artistry of bringing out
their charm and beauty to the fullest.
We offer exclusively unique diamonds, each with its distinct allure.

5 Excellent Diamond

5EX diamonds that brighten up the couple with the finest sparkle.

Of the 4Cs that evaluate diamonds, the only one that we humans can be involved in is the diamond cut technique. The "Excellent" standard is broken down into three elements, each of which has a higher standard of brilliance than that required by the standard "Excellent". The 5EX diamond requires exceptional skills to meet strict standards, along with the quality of the gemstone itself, which is capable of producing such brilliance. These diamonds symbolise ith's approach to craftsmanship, where no time or effort is spared.




Reflection(リフレクション)とは、反射という意味です。ダイヤモンドのファセット面が3次元的に規則正しく配置されているものを、Reflection EXと評価します。 ダイヤモンドが大きな輝きを生み出すには、取り込んだ光を漏らすことなく反射し、できるだけ多くの光を返すことが必要で、そのためには立体的に対称であることが求められます。 一般的なSymmetryは2次元的な対称性の評価ですが、Reflection EXは、3次元的な対称であることをダイヤモンドに光を当て、戻ってきた輝きを撮影することで可視化しています。


Surface(サーフェス)とは、鏡面という意味です。ダイヤモンド表面の研磨痕や、表面に影響が出る結晶の歪みがなく、鏡面状態になっているものをSurface EXと評価します。 一般的にはPolishと呼ばれる評価軸でファセット面を10倍に拡大し研磨の状態が検査されますが、Surfaceでは200倍に拡大しても、表面に光を遮るものが何もない状態まで研磨の仕上げが行われています。 Surface EXのダイヤモンドは全てのファセット面が鏡のように、平らでなめらかに磨き上げられることによって、Cut EX/Polish EXのみのダイヤモンドより多くの光を取り込み、小さな光のもとでも美しく輝きます。

Perfect H&A Diamond

The pattern of eight heart marks and eight arrows, which appears when looking through a diamond with a special scope, is called "Hearts and Arrows" (H&A). At ith, we also offer a special diamond called the Perfect H&A, which is a diamond with a particularly beautiful and well-defined H&A pattern that appears immediately and without a single flaw.
Sharing Miracle Crystals

Romantic Couple Diamonds,
ith Diamonds

"ith Diamonds," our unique program, provides a pair of diamonds cut from a single diamond rough that has taken billions of years to shape.

At ith, we embrace the Sarine Technologies Diamond Traceability Program from Israel, a diamond-related company. We issue certificates that not only vouch for the origin and production process but also symbolize the enduring journey of love, ensuring transparency in the sourcing and crafting of our diamonds.

Selecting the perfect diamond for you

Diamond of Your Choices
from our Extensive Archive

Our artisans at the atelier will assist you in finding the finest diamond by carefully comparing numerous loose stones.

With Reliable Partners

With Reliable Partners

ith, a brand that began with a single artisan. We have partnered with suppliers who possess some of Japan's top cutting-edge technology, resonating with our sincere approach to craftsmanship. The diamonds available for your precious rings are carefully selected by ith's founder, Ayu Takahashi, following a meticulously chosen route to reach you.

Engagement Rings

The diamonds of an engagement ring gives the shape to the wearers' wishes and the affection of the one who gave it.
In addition to size and quality, the first glance and feeling of the diamonds are also important.
No two pieces of diamonds are the same, and the once-in-a-lifetime encounter with it enhances the special meaning of the ring.
The one and only diamond with the special ring design creates a unique ring that is just for the two of you. Proudly crafted in Japan, for loving couples in Singapore.

Eternity Rings

The eternity rings, with the name meaning eternity, are designed to symbolise eternal love with the uninterrupted row of diamonds.
The key to the eternity ring style is a neat row of diamonds of the same size.
By unifying the size or color, the beauty of this ring design is accentuated.
Our in-house artisans, who are particular about aesthetics and craftsmanship, will select and set each melee diamond on a ring one by one.


4C The Diamond 4Cs

The diamond 4Cs are derived from the initial letters of the four categories used to evaluate a round brilliant cut diamond.
The 4Cs are: Carat(weight), Color(shade), Clarity(transparency), and Cut(brilliance).
This standard was proposed by the GIA (Gemological Institute of America) in the mid-20th century.
By establishing clear indicators for the evaluation of diamonds, which until then had been left to the subjective judgment of jewelers, a common understanding of the objective evaluation of individual diamonds was created.
Until these days, the diamond 4Cs are accepted around the world, and well-known high jewelers also use the diamond 4Cs to evaluate diamonds.


  • 6.5mm 1.00ct
  • 5.8mm 0.70ct
  • 5.1mm 0.50ct
  • 4.8mm 0.40ct
  • 4.3mm 0.30ct
  • 3.8mm 0.20ct
  • 3.0mm 0.10ct

Although often thought of as a unit of size,carats are a unit of weight for gemstones,
with one carat weighing 0.2 grams.
It is said to derive from the Greek word "Kararation," which means locust bean,
since in ancient times locust beans (carob beans) were used as weights to weigh gemstones.


  • D, E, F Colorless
  • G, H, I, J Near Colorless
  • K, L, M Faint Yellow
  • N, O, P, Q, R Very Light Yellow
  • S, T, U, V, W, X, Y, Z Light Yellow

Diamonds are often slightly yellowish with nitrogen,
and the closer to pure colorless transparency, the rarer and more valuable they are.
The color rating is divided into 23 alphabetical grades, from the highest grade D, to the lowest grade Z.


  • FL/IF Without inclusions
  • VVS1/VVS2 Inclusions that are very difficult to detect
  • VS1/VS2 Difficult-to-find inclusions
  • SI1/SI2 Easy to detect, difficult to see with the naked eye
  • I1/I2/I3 Easily detectable with the naked eye.

Clarity indicates the clarity of the diamond, which is evaluated by observing it with a 10x magnification loupe
and comprehensively evaluating the size, number, location, quality, color and prominence of inclusions,
as well as any abrasions or scratches that occurred after the cutting process.
Grades are divided into 11 grades, from "FL (flawless)" with no scratches or defects at all,
to those with inclusions visible to the naked eye.


  • Excellent
  • Very Good
  • Good
  • Fair
  • Poor

Cut is the only element in which humans can be involved in the evaluation of a diamond.
The diamond is graded on a five-point scale based on ideal proportion, with the beauty of the polishing, technical cutting skill, and other factors being evaluated using a subtractive point system.
We can select the diamonds that best suit your tastes and preferences, or you may select the diamonds yourself.
A certificate of authenticity will be included with the diamond.
We offer a variety of diamonds to suit all budgets.

Triple Excellent

A diamond's cut grade is based on three factors: proportion (shape), polish (polish condition), and symmetry. Triple Excellent diamonds are diamonds that have been cut with the highest degree of precision and have received the highest rating of "Excellent" for all three elements. Because ith is a brand started by an artisan, we do not compromise but use only the finest diamonds cut by the skillful diamond cutters.

Hearts & Arrows

Among round brilliant cut diamonds, those that are finished with a certain level of symmetry show a pattern of eight arrows on the table side and eight heart marks on the culet side when viewed through a special scope. Diamonds that produce this pattern are called "Hearts and Arrows" (H&A), and are one indicator of a diamond cutter’s high level skill.
At ith, we also offer a special diamond called the Perfect H&A (Hearts and Arrows), which is evaluated from our own perspective. H&A is certified by domestic grading organizations in Japan, but there is a wide range of tolerance in the expression of patterns and considerable individual variation.

ith's Conditions of a Perfect H&A Diamond

When looking through a scope, all eight hearts and arrows appear immediately. No matter how many times you look through a scope, there will always be hearts and arrows without missing one piece. The shape of the pattern should be easily identified as hearts and arrows(in the case of arrows, ones with big arrowheads and short shafts will be inspected as a beautiful shape of arrows).

Shape The Shape of Diamonds

When we talk about diamonds, we usually mean round brilliant cut diamonds.
However, there are a wide variety of diamond/gemstone cuttings.
At ith, we take orders with the diamond shape of your choice.
You may express yourself through the shape of the gemstone.
From princess cut diamonds to hearts or marquises.
Please choose one according to your own preference

Grading Report

The following standards apply to diamonds handled by ith. A certificate of domestic grading organization is available upon request.

Carat 0.2ct〜 ※Except for Fancy Cut Diamonds
Cut Excellent
Color D~H
Clarity IF~VS

Propose Propose with a Diamond

For you, who want to propose to your partner with an engagement ring, yet don’t know the ring size.
To propose with a diamond may be the answer to such a problem.
By doing so, you may take your time to choose the ring design after the proposal has been successfully made.
The diamond proposal might be the ideal way for both of you.