Why does a search for the Hanja in the Korean word 순진(純眞)하다 yield pictures of Japanese Whetstones?
There's a couple of things going on here:


「眞」is not used as a character representing common vocabulary in Chinese and Japanese anymore, being totally replaced in those two languages with the 略字 (약자, abbreviated character) 「真」. In Japanese,「眞」retains some usage for proper nouns, while in Chinese「眞」is not used at all, unless quoting ancient texts.
Korean mixed Hanja-Hangul script is not really used anymore, so Google's search function will prioritise Chinese and Japanese search results when Chinese characters are used as a search term.
Based on (1) and (2),「純眞」will highly prioritise a Japanese proper noun, if it exists as a result. In this case,「純眞」happens to be part of the name of a product.
Based on (1), if you want to search for images relating to the meaning「純眞」, you need to use「真」if you're using a non-Korean search engine.