How to give a shape a mirror finish in Photoshop?

Question

Design

Hello! In the course of creating a banner, I came across one problem, the solution of which I can not think of.
I threw in a composition, but the customer requires that the top card be with a mirror gloss, or with something so that the card itself seems more realistic, and not like an illustration. I tried all kinds of lessons, but it still turns out somehow very flat.

The gloss should look something like the way it's done here.

How can I achieve a similar effect? I work mainly with shapes and figures, but I don’t know how to bring them to a realistic look

Answer 1

Because there is no environment, then the correct gloss (i.e. light reflection) would be a softbox, as in the case of subject photography for example . Those. beautifully placed translucent white square :)
upd. And if you strive for realism, then there should be a shadow on the cards from below.