Nakano Kagaku Iridescent Stainless Cutlery Set (4-Piece)

Iridescent stainless cutlery · Oxide coloring · Nakano Kagaku · Tsubame, Niigata

Color made without paint

What makes IROAI so captivating is its vivid colors — yet none of them come from paint. The color is created by a technique called oxide coloring.

Oxide coloring gives stainless steel color without any paint or dye. The key is a transparent film on the surface of the steel, so thin it cannot be seen. Light reflects in two places: off the surface of this film, and off the steel beneath it. IROAI's hue emerges where these two reflections overlap — the same principle that makes a soap bubble shimmer. And because the color comes from reflected light, it shifts subtly with the angle. Tilt a spoon in your hand, and you can watch its color change — a small pleasure at the table.

Which color appears depends on the thickness of the film. Nakano Kagaku, the Tsubame-based specialists behind IROAI's color, adjusts it in steps of one ten-thousandth of a millimeter to draw out each intended color. Even slight changes in conditions can shift the result, so producing the same color consistently is far from easy. The processing data accumulated to achieve it now runs to tens of thousands of records.

Each IROAI color appears only when the choice of material, the polish, and the oxide coloring conditions align exactly. This iridescent cutlery is the result of that long process of trial and error.

Rooted in Tsubame-Sanjo's metalworking

Tsubame-Sanjo in Niigata has been a center of Japanese metalworking for more than 400 years. Tsubame alone produces over 90% of Japan's metal cutlery. Here, each stage of making — shaping, polishing, and surface finishing — is handled by specialists who have spent generations refining their own part of the process.

IROAI brings two of these specialists together. The cutlery is made by Yamazaki Kinzoku Kogyo, whose cutlery has been used at the Nobel Prize banquet. The color is added by Nakano Kagaku, a surface-finishing company founded in Tsubame in 1956, which has been developing its oxide coloring since 1993.

Two finishes — two different qualities of light

Mirror
Polished to a mirror finish by craftspeople in Tsubame-Sanjo before coloring. The colors appear light and luminous, shifting like a rainbow across the surface. Smooth to the touch at the lip.

Mirror — Blue

Matte
A fine matte texture is created before coloring, giving deeper, quieter color with less flash. Works equally well alongside natural wood tableware, lacquerware, or contemporary ceramics.

Matte — Blue

IROAI Matte — five colors, all made by light

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