Prior to the release of Prifddinas batch two, its examine text was: "The elves would be very interested in these shards. You'll be able to claim a reward when the city opens." and its destroy text was: "The elves would be very interested in seeing these items. It's best to hang on to them for now."
They originally appeared after every hour of skilling, in a player's inventory (or in the bank if inventory is full), while wearing the Crystal amulet (or shiny/sparkling leaf clover necklace from Treasure Hunter). When one was received by wearing the amulet, the following message was shown: "Your crystal amulet has produced a crystal motherlode shard."