Japanese Coin Market Index
Composite and category-level indices for the Japanese antique coin market. Calculated from auction hammer price data.
Index Calculation Methodology
Each index is calculated by comparing the median hammer price of recent auction results within a category against the previous period median, then deriving the rate of change. The index is displayed as the base value (10,000) multiplied by the rate of change. The composite index uses the average rate of change across all categories.
Data Period
- - Hammer price data from the past 90 days
- - Compared against the prior 90–180 day period
- - Fewer than 3 records treated as DEAD
Price Data Collection
- - Hammer prices from major domestic auctions
- - Median value adopted per category
- - Reflected on a rolling basis as data is updated
Composite Calculation
- - Average rate of change across all categories
- - Displayed against base value of 10,000
- - Only categories with data are included
Market Commentary
Updated: June 2026
Each category index is automatically calculated from the latest auction hammer price data. HOT categories indicate strong demand and rising prices, while COOLING signals weakening demand. For detailed category analysis, see the Market Heatmap page.
Related Pages
Disclaimer: This index is provided for reference purposes only and does not guarantee future prices. The data used to calculate the index is based on domestic auction hammer prices and may not fully reflect the entire market. Investment decisions are made at your own risk; please consult a specialist as needed.