Regarding the proposed badge for HMS Emerald I think it was abandoned of political reasons. I've just read a little of the Irish history in the twenties. With the rebellion and the starting process for the independent Irish Free State (1947 The Irish Republic) I figure it would have been political sensitive giving a Royal Navy vessel a badge with a clearly Irish motive. No doubt that the namegiving Emerald was intended to be a cadeau to the green island. I'm not sure, but I think it was Queen Victoria who called Ireland her emerald in the empire.
My conclusion is, that Novice's badge was the original, but it never came in use