I. Varieties of Goldfish Medals
2. Another variety of the original brass medal, with modification to the die (scarce)
3.Restruck brass medal with frosting effect (reverse defect from the die)
4. Silver medal (variety 1), 22.3 grams without packaging
5.Silver medal (variety 2)
6. Silver medal (variety 3)
7. Gold plated restrike, striking followed by plating (about three varieties, with frequent die defect in the middle of the reverse)
8. Silver plated restrike (with the contrast between mirror and frosting, plating before striking, with frequent die defect on the reverse)
9. Silver plated brass restrike, no frosting, striking before plating (about three varieties, with frequent die defect in the middle of the reverse)
10. 1990 silver medal (variety 1)
11. 1990 silver medal (variety 2)
II. Mr. Feng's comments
1. Shanghai Mint produced a large number of gilt medals at a later time, basically in the 1990's. Judging from the medals themselves, their plastic pouches and boxes, we can conclude that gold and silver plated medals were restrikes.
2. It is possible that the mint recycled brass medals stored for many years (normally with some oxidation) by plating them with gold and silver before selling them on the market.
3. The mint would keep some dies (used but still in good condition, meeting production standards), and use them to strike commemorative medals after a long interval of many years.
4. Some varieties have not been seen, but they may exist. That's why I remarked "about 3 varieties".
5. Some of the silver plated goldfish medals have contrasting mirror and frosting, but they are considerably lighter than silver medals. The silver medals weigh about 22.3 grams without packaging. The plate-then-strike technique was adopted by Shanghai Mint rather late.
6. Restrikes often have die defects in the middle of the reverse (the side with the goldfish drawing). This may have resulted from production in large quantity, with less strict quality control on finished products. Such defects were found in other Shanghai Mint commemorative medals, too. In the 1980's, the mints had been rigorous in their work. Proof commemorative medals had high prices, with strict quality standards. Defects like these were seldom found then.
7. (This is the answer to my question on how the Dragon Eye has different aquatic plant shapes) The different shapes of the aquatic plant should have occurred during die making. When a mint strikes a large number of coins, each die has its strike life, and many sets of dies are needed. Differences can occur during the replication of working dies. This often happens to modern Chinese coins and medals. My guess is the following: the mintage of the original brass medals was small; the silver medals with one goldfish on the reverse were probably struck a little later than the original brass medals, with unknown mintage, using several sets of dies; and the "leaf missing with stem connecting the tail" variety may be the result of the die worker adding a line (stem) to the "leaf missing with no stem connecting the tail" variety, to make it look better.
8. (This is an answer to my question about badon's remarks on the cartwheel effect on the silver plated set.) The brightness and smoothness of the mirror field vary on many coins and medals, mostly caused by worn dies or different manual polishing. Many factors can lead to radiating striations and halo effects due to uneven surface on the coins/medals, such as: the physical properties of the material used, high/low striking pressure, precision of die mounting, uniformity of striking pressure, precision of die polishing, the relief and field on the dies. The mints have been striving to improve the quality of the surface on large silver coins, to reduce radiating striations and edge burrs. Recent internal documents from Shanghai Mint touched on these topics. I wrote specifically on the issues of radiating striations on silver coins.
9. Shanghai Mint has precedents of "brass before silver". Brass medals were struck first, and then the same dies or replicated dies were used to strike commemorative medals with precious metals, for example: 60 mm God of Longevity, 60 mm Great Wall, various small lunar medals, and the 80 mm God of Longevity from Shenyang Mint. The reason to use brass first was probably to test the market with cheap material, to avoid the risk of precious metal products with poor sales. Restrikes are usually classical and distinctive products from the mints, with no specific timing to commemorate a person or an event.
10. It requires a comprehensive view to determine the sequence of strikes of coins and medals. In addition to the coins and medals themselves, original packaging, boxes, COA, promotion booklets from the mints, internal documents and similar coins/medals have to be taken into consideration. The more information gathered, the closer the judgment. For example, after obtaining precise information, it was found out that some large size kilo gold and silver coins were struck by Shenzhen Guobao Mint using dies from Shanghai or Shenyang Mint for gold and silver coins released years ago.
Without access to internal documents at the mints, the ocean of coins and medals can only be explored by collectors through tireless efforts.