These are gorgeous old gold coins from Japan. They come in 5, 10, and 20 yen denominations all carrying the same pattern. The first step of evaluation is to determine the denomination and gold content:
5 YEN: 17 mm diameter, 0.121 troy ounces gold
10 YEN: 20 mm diameter, 0.241 ounces gold
20 YEN: 28 mm diameter, 0.482 ounces gold
The next step is to determine the dynasty. These were minted during Meiji, Taisho, and Showa dynasties beginning in years 1867, 1911, and 1925, respectively. You can determine the dynasty by looking for the Japanese symbols shown here. For a thorough explanation of Japanese dating, click to AllCalendars.net. The coin in our picture is from the Showa dynasty.
Next, determine the value due to gold content alone. Look up the current value of gold (it changes every day) at web sites such as kitco.com, then multiply by the ounces of gold in your coin. If you have, say, a 10 yen coin and gold is selling at $1700 US dollars per ounce, the base value due to gold content is 0.241 x $1700 = $410.
Finally, these coins accrue value from coin collector demand. This is value over and above the base gold value. Here are some approximate values to add for collector demand. These are very general guidelines and, if you have a nice-looking example of one of these coins, seek out a knowledgeable collector or dealer who can do a first-hand, in-person appraisal. If your coin is valuable, there are several steps you should take to preserve the value of your coin.
NEVER CLEAN A COIN. CLEANING RUINS VALUE.
5 YEN MEIJI:
worn: add $200 to base gold value
average circulated: add $300
well preserved: add $500
fully uncirculated: add $1000
5 YEN TAISHO:
worn: add $200 to base gold value
average circulated: add $300
well preserved: add $500
fully uncirculated: add $1000
5 YEN SHOWA:
worn: add $20000 to base gold value
average circulated: add $30000
well preserved: add $40000
fully uncirculated: add $60000
10 YEN MEIJI:
worn: add $50 to base gold value
average circulated: add $80
well preserved: add $100
fully uncirculated: add $200
20 YEN MEIJI:
worn: add $100 to base gold value
average circulated: add $300
well preserved: add $500
fully uncirculated: add $1200
20 YEN TAISHO:
worn: add $100 to base gold value
average circulated: add $300
well preserved: add $500
fully uncirculated: add $1200
20 YEN SHOWA:
worn: add $15000 to base gold value
average circulated: add $25000
well preserved: add $35000
fully uncirculated: add $40000
The coin in our picture comes from Heritage Auctions and is dated Showa 7, or 1932. It is an extremely rare coin. CoinQuest thanks Heritage for use of their coin photo.