The 1876-S is among the rarest With Motto eagles from the San Francisco mint. Only 5,000 were made and around five dozen are known, mostly in the VF-EF range. There are likely fewer than 10 known in properly graded AU and virtually all are in the 50 to 53 range. The single finest known is likely the PCGS AU55 which sold for a record-setting $22,325 as Stacks Bowers 11/13: 2223.
This example has a lot of “body” remaining for the grade and it is superior to the other AU53′s which I have seen. It is very lustrous and less abraded than normal with small, scattered marks seen mostly on the obverse. There is some rose-gold toning contrasting the light yellow-gold and the strike is sharp with no appreciable weakness at the centers. To the best of my memory, this is one of the two finest 1876-S eagles I have ever offered for sale.
An inferior PCGS AU53, with a large reverse scratch and questionable color, sold for $12,925 as Heritage 3/14: 30385, as part of the extensive Bentley holdings.
This is a solid Condition Census example of this very scarce, low mintage issue and it seems like very good value compared to the PCGS AU55 which was cited above.