Hook: Ceiling HookThe Gree Sphere Lamp decoration fits into a purple ceiling hook.
How to Get a Gree Sphere Lamp Decoration
Cartel Pack Decorations
The Gree Sphere Lamp decoration can be dropped from Gatekeeper’s Stronghold Packs, which were released on the Cartel Market and bought with Cartel Coins. Cartel Packs, including the Gatekeeper’s Stronghold Pack, include a random selection of items from the Gatekeeper’s Stronghold collection of items. You aren't guaranteed to get a Gree Sphere Lamp decoration from a Gatekeeper’s Stronghold Pack, but it is one of the few ways to get a Gree Sphere Lamp deco apart from buying it on the GTN from another player.
If you're looking to get a Gree Sphere Lamp, the easiest way to get it is to head to the Galactic Trade Network (GTN) in SWTOR and buy it with credits from another player. If it's very rare and not available on the Cartel Market, you could try buying from the GTN and hope you get it.