Water Gem appears in 7 version groups since Generation V, a Jewels item in the Items pocket
PokéAPI item 592 of 2,223, Jewels category, Items pocket
Effect, in PokéAPI's words
Water Gem: “Held: When the holder uses a damaging Water-type move, the move has 1.5× power and this item is consumed.”
Games
Water Gem is listed in the text of 7 version groups, first in Generation V
Game index by generation
IIIIIIIVVVIVIIVIIIIX
Named in
Black and WhiteBlack 2 and White 2X and YSun and MoonUltra Sun and Ultra MoonLet's Go Pikachu and Let's Go EeveeSword and Shield