Quality of images

Hey guys,

I am trying to understand the best way to have my pictures uploaded to the site.
I have uploaded all my images like this:
https://imageshack.com/a/img923/2275/6mJe0S.jpg

On my woohoo product page:
https://mrbijuterias.com.br/product/20170906_191902/

The picture of my product is not quite good as it should, hovering the mouse over the image shows the real quality that I was looking for.
But without the mouse over the quality is very poor, I have a post mansory grid holding the products together.

Any ideas?

Thanks!

The page I need help with: [log in to see the link]