New Craft On Items

Just wondering, when does synthesis recipe get add to an Item?

I mean just looked at Star Sapphire and this item and it's craft exist a very long time, but no recipe there.
How the crafts for items get add here on FFXI-AH? so you can see materials/average cost for Synthesis and price for crafted Item and what you can do with it like on other stuff too? I know some posted info for it, but just wondering about the ffxi-ah feat. like on other items.
Would be cool when it would be there... kinda

Greetings Mindi