I´m trying to correct the quality of my images in my gallery as you say in 
http://forum.muffingroup.com/betheme/discussion/comment/78116/#Comment_78116  but still the same... 
I change as you said: Thumbnail size: 300 x 300 but still blurred... 
I´m using this: 
<div class="fancy-gallery">
[gallery  columns="3" link="file" ids="87,84,96,85,86,95"]
</div>
Could you help me please?
Thanks in advance
                
Comments
please take a look at http://forum.muffingroup.com/betheme/discussion/938/problem-with-image-size-in-shop-slider-media-images-settings-sizes where we explained how to sort images quality. If you changed sizes, you probably forgot to to use Force Regenerate Thumbnails plugin to refresh images.