Blonde or Golddust Yorkshire Terriers cannot make black or brown pigment, so the only pigment they can “express” is gold in various shades from reddish gold to very light gold.  Because these Yorkies cannot make other colors, they “mask” or hide color patterns like Merle and Brindle.  They also “mask” Sable and KB (solid black or brown/no tan).  When a Blonde/Golddust is also a Chocolate, the hair will be gold and nose/foot pads will be brown instead of the normal black.