Our passion lies in curating a diverse and exclusive collection of diamonds, ensuring that every stone meets the highest standards of brilliance and beauty. Whether you’re seeking a rare gem or a timeless classic, R T Diamonds is your trusted source for exceptional quality.

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New Products

Explore the Newest Additions to Our Collection.

0.912 ct
Very Light Brown
SI1

$ 1,038

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0.043 ct
Fancy Vivid Pink
SI2

$ 1,963

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0.135 ct <br> Fancy Intense Blue <br> VS2

0.135 ct
Fancy Intense Blue
VS2

$ 14,815

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0.191 ct <br> Fancy Vivid Yellow <br> SI2

0.191 ct
Fancy Vivid Yellow
SI2

$ 445

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0.951 ct
Fancy Blue Green
VS1

0.432 ct <br> Green Color <br> Cushion Shape

0.432 ct
Green Color
Cushion Shape

$ 3,704

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0.239 ct <br> Fancy Vivid Yellow Green <br> SI2

0.239 ct
Fancy Vivid Yellow Green
SI2

$ 4,075

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0.259 ct <br> Pink Color <br> Cushion Shape

0.259 ct
Pink Color
Cushion Shape

$ 1,926

Add to cart

0.800 ct
Fancy Brown
I1

$ 741

Add to cart

0.065 ct <br> Fancy Intense Pink <br> SI1

0.065 ct
Fancy Intense Pink
SI1

$ 889

Add to cart

Engagement Rings

Our engagement rings are custom-made, designed uniquely, and handcrafted by top Japanese artisans, ensuring a beautiful and one-of-a-kind symbol of your love.

Engagement Rings

Our engagement rings are custom-made, designed uniquely, and handcrafted by top Japanese artisans, ensuring a beautiful and one-of-a-kind symbol of your love.

Exceptional Services
Tailored To Your Every Need

Certified
Diamonds

All of our diamonds are certified by trusted certifying laboratories

Lifetime
warranty

You'll enjoy a lifetime guarantee on any resizing, polishing or coating by our expert staff.

Custom
Design

Create a unique piece of jewelry or choose from a wide variety of designs to fulfill your preferences, including rings and necklaces.

Proven
expertise

Serving customers worldwide for many years, we offer a wide range of imported diamonds to suit all budgets.

The Spark
Runs In The Family

R T Diamonds is a third-generation family business with 15 years of proud presence in Japan. We are committed to sourcing the highest quality diamonds from around the world and bringing them directly to discerning customers in Japan.

Our passion lies in curating a diverse and exclusive collection of diamonds, ensuring that every stone meets the highest standards of brilliance and beauty. Whether you’re seeking a rare gem or a timeless classic, R T Diamonds is your trusted source for exceptional quality.

NOW

THEN

Customer’s Reviews

Yonejiro

10:58 03 Oct 25

①豊富なダイヤモンドの在庫
まるで宝石箱を覗いた時の様な、様々なファンシーカラーの数々。
カラーダイヤは高価なものばかりとのイメージがありますが、手頃に買えるお値段のダイヤもあります。
写真で見た時と実際の色味の感じ取り方が違うのでので、店舗で見ることがおすすめです。

②ダイヤモンドの色味に合わせたジュエリーの仕立て
・カメレオンダイヤ→ロジウムメッキなしの温かみのあるホワイトゴールド。
・ピンクメレダイヤ→少し赤みが強いピンクゴールド。
・カラーレスダイヤ→透明感を引き立てるプラチナ

それぞれのダイヤを引き立てる地金によって、ダイヤの美しさが一層増しています。

③親しみやすいスタッフ
会話の中で自分だけの特別なダイヤを探す楽しみがあります。
「どんな場面でつけるか」「自分の肌に馴染むのはどれか」など自分に寄り添った提案をしていただけます。
どのスタッフともフレンドリーで、喫茶店で友達とおしゃべりをしている雰囲気で楽しく過ごせました。

④ルース、既製品
ルースからジュエリーに仕立てることも、既製品の中から選ぶこともできます。
ルースから選んだ際はカット形状を考慮したデザインを一緒に考えていただけました。
後日LINEでその写真も送っていただけ、出来上がった時のイメージもしやすかったです。

① Wide range of Diamonds
It feels like opening a treasure box—so many beautiful fancy-colored diamonds shining in there. People often think colored diamonds are all super pricey, but they actually have plenty at reasonable prices too. the color can look a bit different in photos, it’s best to stop by the store and see them.

② Jewelry That best much for Each Diamond’s Color
* Chameleon Diamonds: Warm white gold without rhodium plating.
* Pink Melee Diamonds: Pink gold with a slightly reddish tone.
* Colorless Diamonds: Platinum that really highlights their clarity.
They really know how to choose the metal is suitable for every color diamond.

③ Friendly Staff
It’s fun chatting with the staff while looking for my perfect diamond. They’ll help you find something that matches my skin tone or fits the kind of occasions you’ll wear it for. Everyone’s super friendly—it honestly feels like chatting with friends at a cozy café.

④ Loose Stones or Ready-Made Pieces
You can pick a loose diamond and have it made into jewelry, or choose from ready-made designs. If you go with a loose stone, the staff will help you come up with a design that fits the cut perfectly. They even send you photos later, so it’s easy to picture what the finished piece will look like!

① 各种各样的颜色钻石
走进店里就像打开了一个宝盒！ 很多人觉得彩钻一定很贵，其实这家商店也有价格合适的钻石。 照片和实物的颜色多少会有点差异。有时间的话，建议来店里看看！

② 让钻石更闪的搭配设计
* 变色钻 → 无镀铑的暖白K金，自然又温柔。
* 粉色配钻 → 带点红调的粉色K金，甜而不腻。
* 无色钻 → 用铂金衬托，更显清透闪亮。
不同的金属能完美衬托钻石的颜色，让每颗都更出彩。

③ 贴心的店员
一边聊天一边选钻石真的很有趣。 他们会帮你挑出适合肤色、适合场合的那一颗。 每位店员都超友善，氛围就像在咖啡馆和朋友聊天一样轻松愉快。

④ 裸钻 & 成品都可以
你可以从裸钻开始定制，也可以直接选成品。 如果是从裸钻定制，店员会根据切割形状一起想设计方案。 之后还会发照片给你，我可以想象成品会是什么样子，超贴心！

中村賢二

13:55 06 Aug 25

レッドダイヤをはじめ、ここでしか出会えない、貴重なカラーダイヤがたくさんあります。そして、色はもちろん、希少性、クラリティもすばらしいものばかりで、ダイヤモンドファンにはたまりません。
子どもと共に何度か伺っていますが、社長のロイさんをはじめ皆さんにあたたかく迎えていただき、いつもゆっくり見ることができます。これからもお世話になりたい素晴らしいお店だと思います。

中村賢二

13:55 06 Aug 25

There are many precious colored diamonds, including red diamonds, that can only be found here. Not only are the colors amazing, but the rarity and clarity are also superb, making it a must-see for diamond fans.
I've been here several times with my children, and the president, Roy, and everyone else there are always so warm and welcoming, allowing me to take my time looking around. This is a wonderful store that I would like to continue using.

ともとも

07:16 29 Apr 25

結婚&勤続15年の節目のご褒美に、大好きなピンクダイヤをチョイスしました🩷
仕事柄パーティや表彰式もあるので存在感と華やかさがあり、なおかつお客様先でも嫌味のない品の良いサイズ感にこだわりオーダーしました✨
上品な輝きに毎日うっとりです。可愛くて可愛くて嬉しくて〜たまりません💕
素敵なダイヤに出逢えて本当によかったです。ありがとうございました。

ともとも

07:16 29 Apr 25

I chose my favorite pink diamond as a reward for my marriage and 15 years of service🩷
Since I also have parties and award ceremonies due to my work, I ordered a size that has a presence and glamor, and is classy and not offensive to customers.
I am enchanted by the elegant shine every day. So cute, so cute, so happy ~ I can’t get enough of it 💕
I'm really glad that I was able to meet such a wonderful diamond. thank you very much.

R M

04:56 29 Apr 25

カラーダイヤモンドの指輪をオーダーしたくて、色が変化する不思議さに惹かれ、珍しいカメレオンダイヤモンドを選びました。
温度や光によって、オリーブグリーン、レモンイエロー、オレンジ等、色が見る度に違うことに毎日驚いています。
３つのダイヤモンドをデザイナーの方がバランスよくデザインして下さって、世界にひとつだけの最高のmy指輪✨💍✨ができました。
いつも右手に輝いています。

R M

04:56 29 Apr 25

I wanted to order a colored diamond ring, and I chose the rare chameleon diamond because I was drawn to the mysterious way it changes color.
Every day I am amazed at how different the colors are, such as olive green, lemon yellow, and orange, depending on the temperature and light.
The designer designed the three diamonds in a well-balanced manner, resulting in my one and only best ring✨💍✨.
It's always shining on your right hand.

kazu iwa

07:24 01 Mar 25

RTdiamondのロイ・トラビン社長と出会って数年経ちますが、いつも高品質のカラーダイヤを購入させて頂いております🎵💎今回も無色ダイヤとイエローダイヤとの組み合わせでピアスとネックレストップを自作しました👍社長もスタッフの皆さんも気さくで相談しやすいので納得いく品質のダイヤをお探しなら是非一度お訪ねください‼️

kazu iwa

07:24 01 Mar 25

It has been several years since I met Roy Travin, president of RTdiamond, and I have always purchased high-quality colored diamonds from him🎵💎This time too, I made my own earrings and necklace top using a combination of colorless diamonds and yellow diamonds. 👍The president and all the staff are friendly and easy to talk to, so if you're looking for diamonds with the quality you're looking for, please come visit us! ️

Y O

09:46 23 Feb 25

男性がダイヤモンドが付いた指輪をつけるのはどうかな？と不安でしたが、大満足の出来でした。
石は色が変化するカメレオンダイヤを選びました。
温度や光によってグレーがかったグリーンからイエローっぽく見えたりと楽しさいっぱい。
デザインも何度も相談に乗っていただき、イメージ通りの仕上がりです。
イケオジに向かって一直線です。
丁寧なご対応ありがとうございました！

K Y

04:11 28 Jan 25

結婚10周年の記念にハーフエタニティリングを作っていただきました。
全く知識なくオーダーすることになったのですが、ダイヤのサイズのイメージ、カットの種類とランク、留め方など1から丁寧に教えていただき最高の指輪ができました。
キラキラ輝くダイヤが視界に入るたびウットリ見惚れちゃう。
ジュエリーショップ巡りをしてみると素人目にもこちらのクオリティの高さがわかります。
大満足の買い物ができました。ありがとうございました！

Kenta Takamisawa (Doze)

01:53 28 Jan 25

私は長い間ユニークなカラーダイアモンドを探していました。
そしてカラーダイア専門店のRTダイヤモンドへ辿り着きました。

RTダイヤモンドでは社長のロイさんが大変親切に色々なカラーダイヤモンドを見せてくれました。
その中でも最近人気だと言うファンシーホワイトを紹介してもらいました。その色は本当に魅惑的で素晴らしい色でした。
これなら私の彼女も絶対に喜んでくれると確信しています。
とても楽しかったです。また遊びに来ます！

相澤漠（hiro）

13:26 11 Oct 24

ファンシーカラーダイヤモンドをグラデーションで揃えることが大変難しいのは分かっていましたが、ここまで綺麗なものを揃えてくださるとは思っていませんでした。
この完璧なコレクションは、RTDiamondsさんにしか出来ないことだと思います。
夢が叶い本当に嬉しいです。ありがとうございました。

相澤漠（hiro）

13:26 11 Oct 24

I knew it would be very difficult to arrange fancy color diamonds in a gradient, but I never expected you to put together such beautiful pieces.
I believe only RTDiamonds could create such a perfect collection.
I am so happy that my dream has come true. Thank you very much.

Emanuela

01:13 28 Aug 24

結婚が決まり、指輪を探していましたが、個性的なものが欲しいと思いネットで
ＲＴさんを見つけました。
カラーダイアモンドを知らなかったのですが、社長さんがとても親切に説明してくだ
さりました。
とても可愛らしい色があり、目が釘付けになりいつも迷ってばかりの私が
一目ぼれでグリーン色のダイヤモンドを購入しました。
これから、どんなリングにするか相談させて頂き
加工までお願いする予定です。
とても良いご縁をありがとうございました。

Emanuela

01:13 28 Aug 24

I decided to get married and was looking for a ring. I wanted something unique, so I found RT online.
I had never heard of colored diamonds, but the president was very kind and explained it to me.
There are some really pretty colors that catch my eye, and I'm always having trouble deciding what to buy, so I fell in love at first sight and purchased a green diamond.
I'll be discussing what kind of ring I want and will even have it machined.
Thank you for making such a great connection with us.

Dカッシー

03:29 21 Aug 24

I like colored diamonds and wanted to make a ring just for me. I looked at a lot of them on the internet, but I didn't know what to do. That's when I came across RTdiamonds' page. I wanted to see them in person, so I came to the store today. The very kind President Roy showed me many colored diamonds. He also said that he will process them, so he was able to consult with me about the details, such as the design. This time, I purchased the long-desired blue diamond. I'm planning to make a ring from now on. Thank you very much.

Sabrina Mpe

07:04 23 May 24

Such a great experience! Akhil and team helped me finding my dream diamond with always friendly and very competent support … got the shipping well delivered without any problems even to germany … just love my little straight intense blue diamond ! Very fair price and amazing customer support … will definitely be back whenever looking for another fancy diamond ! They have a huge range even in extra rare colors and shapes … thank u so much again ! My full recommendation for R.T.Diamonds to buy ur special diamond !

Yu Ku

12:50 11 Mar 21

I wanted to propose to my (now) wife but had no knowledge about jewelry or diamonds.
I went to different places, and I was very unpleased with both prices and service.
RT diamond were extremely helpful and friendly. They guided me through many details I didn't know, and gave me an amazing price compared to other places.

And most importantly, she said yes!!!🎊

reuben rosen

04:50 27 Oct 20

I have been looking for a perfect engagement ring for a long time. Never could find anywhere that would listen and really hear me and my requests for the ring. RT Diamonds is the place to go to for the special gift for your loved ones. Be it engagement ring or fashion jewelry. They really listen and tailor the perfect piece to your demands and expectations.
Thank you RT Diamonds.

לירן טרוין

15:05 26 Oct 20

I want to recommend RTD, I was looking for the perfect gift for my fiancée. At RTD they made me pink diamond earrings and an engagement ring with a yellow diamond. I received excellent service and personal treatment from the best in the market.
They worked day and night to get my fiancée the perfect piece of jewelry she imagined.
There is no doubt that all the jewelry and diamonds I would like to purchase in the future I will get to RTD

guy

13:24 21 Oct 20

I had the most amazing experience during the purchase process.
The shop has a very kind, quick and professional service.
I was looking for an engagement ring diamond for my wife.
After deliberating between a white diamond or a green diamond i went for a pink diamond in a shape of a heart which was the perfect choice.
My other half loved it and i would definitely recommend on this amazing shop

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