Open a new document with your preferable size (i chose 300x300) with a black background.

Choose the custom shape tool and choose the hexagon amongst all the custom shapes (if it's not present you may need to load all the custom
shapes).



Make a new layer. Choose a light gray shade and while holding the Shift key, draw a hexagon.

Double click the new layer to access Blending options.

Choose Bevel and Emboss. Apply all the settings as shown. Note: you
may want to play with size and soften a little, depending on your
wants and your gem size.





Here's what you should aim for:



Then apply the following settings for Color overlay:
- color #e40942
- opacity 100%




Apply the following settings for Stroke:
- color #ff005a
- size 2px



Make a new layer.

Choose the Polygonal lasso tool and draw a shape similar to this one.




Choose the gradient tool. You'll need a gradient as shown on the picture. Apply it from the outside of the gem to the center, as shown on the picture.





Repeat the same procedure, but this time choose Diamond gradient. Apply as shown, again from the outside to the inside.

Finally choose Overlay as a layer mode.




Grab the Polygonal lasso tool again and draw a similar shape to the one shown below.




You will now need to use the Gradient tool, but this time you'll need a black-to-transparent one, as shown on the picture. Apply it from the outside to the center.



Choose Vivid Light as a layer mode. You will now have something like this for layers and looks.




Finally, return to Blending options (double click on the diamond layer), and apply the following settings for Contour:
- Range 50%




You should eventually end up with something like this: