This item was acquired from a deceased Nihonga (Japanese-style painting) artist who passed away at the age of 100, 20 years ago. The Showa era (1926-1989) "Ebisuya Label Natural Ultramarine/Navy Blue Set 37.6g" has strong antique value in the current market, and its price is incomparable to that of regular artificial mineral pigments. Sets from the early Showa era are rare and could be valued from tens of thousands to over a hundred thousand yen. 〇 Authenticity of this item: Double red lines on a white background → This is a simple yet strong identifier for the above-mentioned Ebisuya product, distinguishable from labels of other art supply stores (such as Hokodo and Kissho). It also indicates that it is a pre-war product (see photos). 〇 About Navy Blue & A Ultramarine Ultramarine and Navy Blue are almost the same color, so the price difference is determined by "frequency of appearance in the market" and "the age of the label and container." Navy Blue is almost the same color as Ultramarine, but due to its scarcity, it commands a "rarity premium." A Ultramarine: Natural mineral pigments were the norm during this period. It was sufficient to write "Ultramarine" without the manufacturer explicitly stating "natural." Furthermore, the "A" at the beginning indicates a higher quality. Navy Blue = 13.44g A Ultramarine = 23.56g 〇 Product name in the center → Often written in letterpress printing or handwritten-style characters. 〇 Attached to test tubes or glass bottles → This was a sales format from the early Showa era to pre-war times, a typical distribution style for natural mineral pigments. Test tube packaging: Mineral pigments from the early Showa era to pre-war times were often sold in small portions in test tubes or glass bottles, which was a typical distribution method for natural pigments. Artificial ultramarine became widespread after the war, so test tubes from this period can be considered natural. ＊ AI Judging Factors: If this Ebisuya label is from the early Showa era and is labeled "Ultramarine" in a test tube, it is a strong basis for judging it to be natural ultramarine. In the modern market, this label itself has "antique value" and is helpful in determining the authenticity of ultramarine. In the early Showa era, "Ultramarine = Natural" was common sense, so it was possible to determine that it was natural from the container and price label without explicitly writing "natural." The photos and explanations are all that is available, so please examine them and we await your purchase.