Great Britain SG#730 3d Dark Purple 1967-1971 Pre-Decimal Machin Heads, A VFNH UR Corner Block, Centre Phosphor Band, Head A, Streaky PVA Gum

A VFNH upper right corner block of the 3d dark purple pre-decimal Machin head stamp, with centre phosphor band, head A, and streaky PVA gum. Printed on HF/HB paper.

Gibbons catalogue is £4. This translates to approximately $8. The block offered here grades 80.

General Notes:

The white chalk-coated papers do exhibit variations under long-wave ultraviolet light. Generally they vary from high fluorescent to hibrite. These differences can be seen from the front of the stamps, but are most dramatic when viewed from the back of the stamps. The attached scan shows just how dramatic these differences can be. The stamps in this lot will exhibit many of these differences, with many stamps having a different fluorescent reading on both the front of the stamp and the back.

In addition to visible and noticeable variations in colour shades in normal light, many of the values in the set show clear differences in the composition of the printing ink when viewed under UV light, with some stamps appearing to be a darker version of their issued colour under UV, some appearing to be a much lighter colour, and others appearing to be a different colour entirely.

The bust of the Queen varies between printings also. Head A has a relatively flat bottom to the bust, whereas Head B has an extra curve added at the base that makes it look rounded. These two types are found on most of the values, though a few are only found with Head C, which is similar to Head B, but with a more three dimensional effect.

In addition to the listed gum differences of PVA and gum Arabic, the PVA gum can also be found in smooth and streaky versions.

Finally the phosphor bands can be found in different strengths ranging from very obvious to the naked eye to almost invisible to the naked eye. Also, there are the listed variations in band orientation, such as 2 side bands, one centre band, 1 side band, etc.