20 Hryven Pure Water

Ukraine launched a "Pure Water" conservation series in the mid-2000s as the Dnieper basin — source of drinking water for roughly 32 million people — faced mounting industrial contamination pressure following post-Soviet industrial neglect and the long tail of Chornobyl's groundwater effects. The bimetallic format, gold centre set in a silver ring, was expensive to produce relative to face value and clearly aimed at the collector market rather than any circulatory function.

The Fridberg reference Fr#25a places this squarely in the catalogued Ukrainian bimetallic gold issues, a short series with low mintages across all titles.