This 1827 Capped Bust Half is the Square Base 2 variant (O-139) and defined by the type of 2 used in the date.  It has a gorgeous steely gray patina and is untoned in protected areas.  A classic look for early silver.  The luster is brought out strongly while rotating under the light. PCGS Retail is listed at $925 for this coin.
 
PCGS Cert.# 40256202