Regarding Showa Era Test Tube-Contained Purple Ultramarine, Light Ultramarine, and Approximately Ultramarine Ultramarine is a very expensive pigment, and it is assumed to be natural. Artificial ultramarine began to be distributed cheaply after the war, so ultramarine from the early Showa era is basically considered natural. 〇 About This Product This product is mineral pigment owned by a Japanese painter who passed away 20 years ago at the age of 100. Most of it is natural mineral pigment, released in the early Showa era in test tubes sealed with corks. 〇 Features of this 3-color set: Ultramarine is mainly derived from azurite, and was classified into "Light Ultramarine," "Burnt Ultramarine," "Black Ultramarine," and "Purple Ultramarine" depending on the particle size and firing. Among this set, the purple ultramarine from the Showa retro era is rare as there are almost no existing ones. "Purple Ultramarine" refers to ultramarine that has a purplish hue due to firing. "Light Ultramarine" is made by crushing and water-separating the raw material: azurite, and separating it by particle size. "Burnt Ultramarine" is a variation obtained by firing natural ultramarine (mainly derived from azurite). It is a classification often seen in the art materials system of the early Showa era, and is positioned as a "calm blue with a purplish hue" among ultramarines. 〇 About Authenticity All three have double red line labels on a white background, proving that they were sold at Kyoto Ebisuya at the time. At the same time, the test tubes themselves from the Showa retro era prove that they are natural materials. 〇 What the containers and labels prove: In the early Showa era, the form of the containers and labels themselves was proof of natural ultramarine. At that time, they were often put in glass bottles or ceramic jars, and paper boxes and plastic containers were rarely used. 〇 Printing style of the labels: There were many labels with letterpress printing or a handwritten style, and the manufacturer's name (Hokodo, Kissho, etc.) was written largely. Since artificial ultramarine was not yet widespread, there was no need to specifically write "natural." 〇 Price: Labels on other containers at the time indicated a price of 4,000 yen for 10g of one ryo, and they are from the same period. It is possible that it would be a considerable amount if converted to current prices. The photos and explanations are everything, so please examine them carefully and we look forward to your purchase.