Hello Mate,
you can add code css to VenusTheme/Template panel/Theme Default/ Customization/ Custome css :

code for New
 
.product-block .image .new-icon {

    background: none repeat scroll 0 0 #44cb9d !important;  change your color here

}

If it is not your problem ,please tell me name your theme, i will check and find you solution