1992年5元三枚一组中国古代科技发明发现系列一。镜面底板,霜面图文。
CHINA. Trio of 5 Yuan Proofs (3 Pieces), 1992. Inventions & Discoveries Series I. NGC PROOF-68 ULTRA CAMEO (2) and NGC PROOF-69 ULTRA CAMEO.。Compass (KM-407), Bronze Age Urn (KM-408), and Seismograph (KM-405). All brilliant with hard mirrored fields and frosted cameo devices.。