Where's my gem?

I need some advise from the knowledgeable.
I cannot seem to get access to Gems by placing a Holy Site upon it. The city is working on that tile and is connected to the capital via road. Still the happiness from Gems doesn't appear in the top right corner. Neither am I trading the Gems to anyone.
Please help me figure this out. I need some happiness badly.

NEVER PUT GP IMPROVEMENTS ON LUXURIES. You can settle on the luxuries if you want, and you will get the happiness after you research the required tech. GP improvements should be attempted to only be placed onto deer, sheep, cattle, horses or iron. Those are the places to put them. Reload your earlier save, and find a new spot for your holy site. You can also send it to the city that has a lot of pop, but lacking in land, likely a jungle one. Just place it away from the river, and not on the luxuries and you'd be good to go. Academies you would always want in your cap.

Basically, as already stated: Great Person Improvements WILL connect strategic resources (Horses, Iron, Coal, Aluminium, Uranium) to your empire, but will NOT connect luxuries.
Cities, however, will connect both if placed right on top.