and showing, on the reverse, a good strike of the rare "CORREIO/MACAO/21 JUL 1851" d.s. in black with Hong Kong c.d.s. alongside, fine" /> cover 1851 (21 July) entire letter to Gibraltar, rated<I> "4"</I> and showing, on the reverse, a good strike of the rare "CORREIO/MACAO/21 JUL 1851" d.s. in black with Hong Kong c.d.s. alongside, fine | Christie's