1899, 6¢ lake, overprinted "Specimen" in purple (Scott 6SE), o.g., never hinged, remarkably fresh and Fine. Scott's value is for "fine-very fine appearing examples with minor faults".
Scott $175 ++. (Image)

Estimate $150-200

1899, 10¢ brown, type I (Scott 8), fuyll wide bottom margin imprint and plate number block of 6, slightly tropicalized o.g., fresh and solid, about Fine.
Scott $1,250. (Image)

Estimate $400-600

Guam Guard Mail Overprints, Small Collection, comprises mint #M5-M11, two used M6 (one with a rounded corner), a philatelic cover with a pair of M5, two commercial covers of M6, one legal size with a strip of 3 from Inarajan to Agaña, a Last Day cover of M7-11, and a legal size Last Day cover of M8 with a Guam Naval Government corner card; also includes more than 30 photocopies of related articles, Fine to Very Fine or better. (Image)

Estimate $150-200

1930 (Apr 8), Guam Guard Mail overprints, 2¢ green & 4¢ carmine (Scott M1-M2), o.g., Fine to Very Fine. Only 3,000 and 2,000 issued, respectively.
Scott $625. (Image)

Estimate $250-350

1930 (Apr 8), Guam Guard Mail overprints, 2¢ green & 4¢ carmine (Scott M1-M2), each tied on a small piece by Agana double-lined double circle datestamp, o.g., Fine to Very Fine. Only 3,000 and 2,000 issued, respectively.
Scott $425. (Image)

Estimate $200-300

1930 ((Jul 10), Guard Mail, 1¢ & 2¢ Guam Seal, small collection (Scott M3-M4), consists of two mint (ungummed) sets, one set showing good portions of the watermark; a "used" 2¢ with an indistinct cancel; a proof of the seal in reddish brown on smooth off-white paper (M3-E2); and three covers: 1.) a 1¢ on a locally used Agaña Military use, Sep 16, 1930; 2.) a 1¢ pair used from Asan to Dr. Jay Miller in Agaña, Aug 25, 1930; and 3.) a 2¢ with a Naval Government of Guam corner card from Agaña to Sumay, Sep 9, 1930; the last with a vertical file fold and top flap missing, otherwise Very Fine. (Image)

Estimate $400-600

1930 (Dec 29), 2¢ Guard Mail, "GRAUD" and "MIAL" Errors (Scott M7a, M7b), o.g., lightly hinged, Fine. Only 500 of each were issued.
Scott $850. (Image)

Estimate $350-500