remove black diamonds with a question mark

Hi Alex Asimakopoulos,
I need a closer look to detect root of issue as you said, let’s provide me the admin and ftp credential of your site.
Regards,
Mall.

Hi Alex Asimakopoulos,
I have created a backup and edited the template file at: 
/app/design/frontend/ubertheme/market/template/joomlart/jmproducts/sales.phtml
and the issue was solved in your site.
Solution:
Find to the code:

echo strip_tags(substr($product->getName(), 0, 25)).'...';

and replace it by:

echo strip_tags(mb_substr($product->getName(), 0, 25, 'utf-8')).'...';

Regards,
Mall.