Emerald Imperium Palace

You take an Emerald and start to imbue a large amount of power into it creating you own temporary plane of existence.

This Emerald then starts to float 1 and 1/2 ft off the ground and it can't be moved by anything less than a wish spell. This Emerald can't be destroyed or dispelled if any living creature is inside the emerald. Once the spell is over all living creatures are ejected from the emerald and the emerald gently falls to the ground. The spell's timer can be rest by the caster if they go outside the gem and use 2 4th level spell slots or one of any higher level spell slots.

Then anyone who the caster allows, can touch the emerald and can go into the emerald, where there is a mystical palace that can be customized by the spell caster at their whim, there is an infinite supply of feed and drinks in the palace, with a maximum of a 50,000 ft. by 50,000 ft. space. With in the large space you can have whatever you want except spell components, anything the caster wants can be there and will stay there, no real world items can stay in the gem and no item made in the place can come out of the gem. While in the gem you are immune to all detection spells except that a floating emerald is pointed out (be it detect magic or the Scrying spell it just shows the emerald floating). No spell can target you from outside the gem (except Sending), though nor can you cast a spell to a creature that is outside the gem if you are inside it (except Sending).