One of the questions my technicians get asked frequently when out and about doing maintenance is how we make our plants so shiny. I am happy to explain, though you may not like the answer if you were thinking of buying some!
We use a product called Pixie Sparkle. No, I'm not joking. Here's a pic:
We dilute this down to almost homoeopathic levels (more than the instructions say) and spray it on in the little spray bottles you see us carrying. It doesn't have a lot of effect the first time, but repeated use gives the plant a natural sheen. The alternative is aerosol leaf shine which (in my opinion) imparts an unnatural 'wet look' shine to the foliage, and can damage the leaves if not used carefully.
You can buy it online from a few places. Here's one place.
But look at the price: now you know why we dilute it so much!
Ahem... what I meant to say is, when you get your plants maintained by Stewarts, no expense is spared!
Jonathan