15c Black, F. Grill (98).
Choice centering, detailed impression, bold quartered cork cancel, Very
Fine, with 1997 P.F. certificate (Image)
24c Gray Lilac, F. Grill
(99). Original gum, lightly hinged, bright shade and proof-like
impression on brilliant white paper, sharp and clearly-defined
grillEXTREMELY FINE BY ANY STANDARDS AND A SUPERB GEM FOR THIS RARE ORIGINAL-GUM EXAMPLE OF THE 1868 24-CENT F GRILL.
The higher-denomination F Grills were produced in limited quantities and seem to have caused National Bank Note Co. difficulty in applying perforations. They are typically off center with very choppy perfs This stamp has uncharacteristically precise centering and well-formed perforations. (Image)
24c Gray Lilac, F. Grill
(99). Disturbed original gum, clearly-defined grill, bright color,
reperfed at right, Fine appearance, a scarce unused example of the 24c F.
Grill (Image)
24c Gray Lilac, F. Grill
(99). Wide margins for this difficult issue, bright color, clear grill,
quartered cork cancel, Very Fine and choice, with 1978 and 1989 P.F.
certificates (Image)
24c Gray Lilac, F. Grill
(99). Rich color, clear grill, unusual large segmented cork cancel,
reperfed at left (not mentioned on accompanying certificate), Very Fine
appearance, with 1995 P.F. certificate
(Image) 
30c Orange, F. Grill
(100). Unused (no gum), extraordinarily choice centering with wide
margins all around, vibrant color and intense impression, bright and
freshEXTREMELY FINE. THE 1868 30-CENT F GRILL IS RARELY FOUND WITH SUCH WIDE MARGINS AND SUPERB CENTERING. THIS STAMP CERTAINLY RANKS AMONG THE FINEST UNUSED EXAMPLES IN EXISTENCE.
The Scott footnote to No. 100 states: "Values for No. 100 are for copies with small margins, especially at sides. Large-margined examples sell for much more." Our best estimate is that no more than a dozen 30c F Grill stamps -- with original gum or unused -- exist with margins and centering comparable to this example. We make that statement after searching auction catalogues for major sales held during the past 50 years.
With 1981 P.F. certificate (Image)
30c Orange, F. Grill
(100). Unused (no gum), virtually perfect centering with perfs clear
all around, vivid color, bright and freshEXTREMELY FINE. THE 1868 30-CENT F GRILL IS RARE IN THIS SUPERB UNUSED CONDITION.
With 1992 P.F. certificate (Image)
30c Orange, F. Grill
(100). Wide margins all around, rich color, clear grill, circle of
wedges cancel, Extremely Fine Gem, one of the most difficult values of the
set to find with such choice centering and wide margins
(Image) 
30c Orange, F. Grill
(100). Clear grill, deep rich color, choice centering for this
difficult issue, well-struck quartered cork cancel, Extremely Fine, with
1999 P.F. certificate (Image) 
90c Blue, F. Grill (101).
Unused (no gum), wide margins, attractively centered, few soiled specks and
tiny scuffsVERY FINE CENTERING AND AN EXTREMELY ATTRACTIVE UNUSED EXAMPLE OF THE 1868 90-CENT F GRILL.
Ex Jennings. With 1961 P.F. certificate stating "sound and uncancelled" (Image)
90c Blue, F. Grill (101).
Clearly-defined grill, intense shade, bold cork bars cancel, Very Fine (Image)