It may not be fake, but it's just a question of whether it's worth it.
Moonstone is called moonstone because it has a "moonlight effect" (a faint blue or bright white halo appears in the center of the gem). Halo will follow the light source, and a really good moonstone halo should be visible from all angles. Therefore, the price of moonstone mainly depends on its aura.
Judging from the photos, the quality of this moonstone is not high. I haven't seen the basic fluorescence or halo, so I don't rule out the problem of photo shooting. You can see this stone for yourself.
The so-called lottery is just a means of promotion for merchants. The price tag of the shopping center is exaggerated, so it is certain to spend half the money. However, the goods you bought in the mall didn't suffer too much.
These are all good photos of moonstone, which can be compared and referenced.