To identify whether a piece of glass is Japanese, here are some key indicators to look for:

1. Labels and Markings

Many Japanese glass pieces, especially from the mid-20th century, were labeled. Look for:

• “Made in Japan” or “Japan” labels.
• Specific brand labels like:
  • Iwatsu Glass – often labeled “Best Art Glass, Foreign” or “Hineri”.
  • Sanyu Glass – labels may read “Fantasy Glass” or “Registered, Sanyu, Made in Japan”
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2. Style and Color

Japanese art glass from the 1950s–1970s often features:

• Bright, swirling colors (e.g., pink, blue, yellow, green).
• Handkerchief-style vases or abstract shapes.
• A style that can resemble Murano or Czech glass, but with subtle differences in finish and form.

3. Craftsmanship

• Japanese glass often has a high-quality finish but may include small imperfections or bubbles, especially in older pieces.
• The glass may feel slightly lighter than European counterparts.

4. Manufacturer Clues

Some known Japanese glassmakers include:

• Iwatsu Glass Co. (Osaka)
• Sanyu Glass Co. (Osaka)
• Narumi (sometimes associated with Sanyu)

5. Compare with Online Galleries

Websites like 20th Century Glass have galleries and identification guides that can help you visually compare your piece 

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