Colorless Round Diamond Rings

ラウンドダイヤモンドリング

GIA・CGL鑑定書付きの天然ラウンドブリリアントカットダイヤモンドリングを豊富にご用意。

ダイヤモンドカットの中で最も輝きが強いラウンドブリリアントカットは、世界で最も選ばれる婚約指輪のシェイプです。

D〜Jカラー、VVS〜SI2クラリティ、0.425ctから1.953ctまでの幅広いラインナップから、18Kホワイトゴールド・プラチナ（PT900・PT950）でご提供しています。¥190,000台から。

サイズ調整無料。カスタムオーダーも承ります。

Showing 27 of 27

Price: Low to High Price: High to Low
  • 18K Round-cut Diamond Ring - 0.453ct

    18K Round-cut Diamond Ring - 0.453ct

    ¥190,000 (Tax incl.)
    NEW
  • 18KYG Round-cut Near Colorless Diamond Ring - 1.019ct

    18KYG Round-cut Near Colorless Diamond Ring - 1.019ct

    ¥420,000 (Tax incl.)
  • 18K Colorless Round-cut Diamond Ring - 0.425ct

    18K Colorless Round-cut Diamond Ring - 0.425ct

    ¥260,000 (Tax incl.)
  • 18K Colorless Diamond Ring Round-cut - 1.196ct

    18K Colorless Diamond Ring Round-cut - 1.196ct

    ¥570,000 (Tax incl.)
  • 18K Near Colorless Diamond Ring Round-cut - 1.087ct

    18K Near Colorless Diamond Ring Round-cut - 1.087ct

    ¥590,000 (Tax incl.)
  • 18K Round-cut Colorless Diamond Ring - 1.362ct

    18K Round-cut Colorless Diamond Ring - 1.362ct

    ¥880,000 (Tax incl.)
  • 18K Round-cut Colorless Diamond Ring - 1.051ct

    18K Round-cut Colorless Diamond Ring - 1.051ct

    ¥540,000 (Tax incl.)
  • 18K Round-cut Colorless Diamond Ring - 1.025ct

    18K Round-cut Colorless Diamond Ring - 1.025ct

    ¥540,000 (Tax incl.)
  • 18K Round-cut Near Colorless Diamond Ring - 1.005ct

    18K Round-cut Near Colorless Diamond Ring - 1.005ct

    ¥480,000 (Tax incl.)
  • 18K Round-cut Near Colorless Diamond Ring - 0.826ct

    18K Round-cut Near Colorless Diamond Ring - 0.826ct

    ¥490,000 (Tax incl.)
  • 18K Colorless Diamond Ring Round-cut 1.352ct

    18K Colorless Diamond Ring Round-cut 1.352ct

    ¥770,000 (Tax incl.)
  • 18K Round-cut Colorless Diamond Ring - 1.168ct

    18K Round-cut Colorless Diamond Ring - 1.168ct

    ¥490,000 (Tax incl.)
  • 天然ダイヤモンドリング 無色 ラウンド SI1 1.953ct 画像

    PT900 Round-cut Colorless Diamod Ring - 1.953ct

    ¥660,000 (Tax incl.)
  • 天然ダイヤモンドリング 無色 ラウンド VS1 0.695ct 画像

    18K Round-cut Colorless Diamond Ring - 0.695ct

    ¥370,000 (Tax incl.)
  • 天然ダイヤモンドリング 無色 ラウンド 0.9ct 画像

    Oval Design Colorless Diamond Ring - 0.9ct

    ¥390,000 (Tax incl.)
  • 18KWG ダイヤモンドリング 0.983ct SI1 ほぼ無色 Near Colorless G ラウンド 画像

    Round Near Colorless Diamond Ring - 0.983ct

    ¥540,000 (Tax incl.)
  • Round Colorless F Diamond Ring - 0.81ct

    Round Colorless F Diamond Ring - 0.81ct

    ¥440,000 (Tax incl.)
  • 18K Colorless Round-cut Diamond Ring - 0.51ct
    Sold out

    18K Colorless Round-cut Diamond Ring - 0.51ct

    ¥290,000 (Tax incl.)
    Sold out
  • 18K Round-cut Colorless Diamond Ring - 2.354ct
    Sold out

    18K Round-cut Colorless Diamond Ring - 2.354ct

    ¥980,000 (Tax incl.)
    Sold out
  • 18K Round-cut Colorless Diamond Ring - 0.696ct
    Sold out

    18K Round-cut Colorless Diamond Ring - 0.696ct

    ¥360,000 (Tax incl.)
    Sold out
  • 18K Round-cut Near Colorless Diamond Ring 0.66ct
    Sold out

    18K Round-cut Near Colorless Diamond Ring 0.66ct

    Contact us for price inquiry.

    Sold out
  • 18K Round-cut Colorless Diamond Ring - 1.303ct
    Sold out

    18K Round-cut Colorless Diamond Ring - 1.303ct

    ¥670,000 (Tax incl.)
    Sold out
  • Round Near Colorless Diamond Ring - 0.257ct
    Sold out

    Round Near Colorless Diamond Ring - 0.257ct

    ¥120,000 (Tax incl.)
    Sold out
  • 天然ダイヤモンドリング ほぼ無色 ラウンド SI1 1.215ct 画像
    Sold out

    Round Near Colorless Diamond Ring - 1.215ct

    ¥770,000 (Tax incl.)
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  • 天然ダイヤモンドリング ほぼ無色 ラウンド VS2 1.45ct 画像
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    18K Near Colorless Round Diamond Ring - 1.45ct

    ¥1,300,000 (Tax incl.)
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  • 天然ダイヤモンドリング 無色 ラウンド 0.5ct 画像 3石
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    18K Colorless Diamond Ring Round-cut (3 Stones) - 0.5c

    Contact us for price inquiry.

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  • 天然ダイヤモンドリング 無色 0.506ct SI1 ラウンド 画像
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    PT1000 Round-cut Colorless Diamond Ring - 0.506ct

    ¥150,000 (Tax incl.)
    Sold out

How to Choose a Round Cut Diamond Ring

What Makes the Round Brilliant Cut Unique

The round brilliant cut was developed in the early 1900s using mathematical principles to maximize the reflection, refraction, and dispersion of light through a diamond's 58 facets. The result is the most brilliant of all diamond shapes — no other cut returns more light to the eye, which is why round remains the world's most chosen diamond shape for engagement rings by a significant margin. It is also the only shape for which the GIA formally assigns a cut grade, ranging from Excellent through to Poor. That grade directly reflects how well the stone handles light — an Excellent grade means the facets are proportioned to produce the maximum possible brilliance and fire. At Weiss, every round brilliant cut diamond ring comes with a GIA or CGL certificate verifying cut grade alongside the other 4Cs.

Cut Grade and Color Grade — Getting the Balance Right

For round brilliant cut diamonds, cut grade is arguably more important than color grade in determining how impressive the stone looks. An Excellent cut G color diamond will outperform a Very Good cut D color diamond of the same carat weight in real-world brilliance, because the superior facet proportions return more light regardless of the stone's color purity. The GIA cut grade scale runs Excellent, Very Good, Good, Fair, and Poor — for an engagement ring, Excellent or Very Good are the grades worth targeting. On color, D through F (Colorless) are the most transparent grades with no perceptible warmth. G through J (Near Colorless) appear virtually identical to colorless grades when set in white gold or platinum, making them excellent value choices without visible compromise in appearance.

Setting Styles for Round Cut Diamonds

The round brilliant cut's circular symmetry makes it one of the most versatile shapes for ring settings. A solitaire setting — typically with four or six prongs — elevates the diamond to allow maximum light entry from all angles and is the most classic choice for an engagement ring. A six-prong Tiffany-style setting is the most recognized solitaire design globally. A three-stone setting flanks the center round with two smaller diamonds, traditionally symbolizing past, present, and future, and is a popular engagement ring choice. A halo setting surrounds the center stone with a ring of smaller round diamonds, creating a larger visual impression than the center carat weight alone. At Weiss, our round cut collection focuses on solitaire and three-stone designs suited to long-term daily wear.

Carat Weight and Budget

Our round cut diamond ring collection starts from ¥190,000 (0.453ct) and extends to ¥880,000 for a 1.362ct VS1 stone. Round brilliant cut diamonds typically cost slightly more per carat than fancy shapes because more of the rough diamond is lost during the cutting process to achieve the ideal proportions. However the transparent grading system — particularly the GIA cut grade — means you can compare quality objectively in a way that isn't possible with other shapes. The most popular range for engagement rings in Japan is 0.5ct to 1ct, which in our collection sits between ¥260,000 and ¥590,000 depending on color and clarity grade. If you need help finding the right balance for your budget, contact us or visit our office in Okachimachi.