PCP = Phosphor coated paper PVAD = Polyvinyl alcohol acetate dextrin gum
ACP = Advanced coated paper PVA = Polyvinyl alcohol acetate gum
FCP = Fluorescent coated paper
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nd54_56_57

Greyish blue

Symbol types

Type 2a - The pearls along the crown are separate from each other Type 2b - The second pearl to the left of the orb is joined to the crown and the first three on the left side of the crown are joined to each other. The bottom pearl underneath the orb is attached to the central cross.

ND54 - Northern Ireland 17p greyish blue, type 2a, PCP/PVAD (Cyls Q1, Q2, Q3, Q4) (Questa/litho) - Deegam N170.1.1 - S.G specialised XNL17 - Stoneham U65 - Concise NI43

PCP, type 2a from cylinders Q1, Q2, Q3, Q4 [23.10.84

ND56 - Northern Ireland 17p greyish blue, type 2a, ACP/PVAD (Cyls Q1, Q2, Q3, Q4) (Questa/litho) - Deegam N170.3.1 - S.G specialised XNL18 - Stoneham U76

ACP, type 2a from cylinders Q3, Q4 [25.2.86]

ND57 - Northern Ireland 17p greyish blue, type 2b, ACP/PVAD (Cyls Q1Q1, Q2Q2) (Questa/litho) - Deegam N170.3.2 - S.G specialised XNL19 - Stoneham U76a - Concise NI43Ea

ACP, type 2b from cylinders Q1 Q1, Q2 Q2 [?.9.86]
nd58

ND58 - Northern Ireland 17p dark blue, FCP/PVA, 4mm 'SA' phosphor bar right of centre CB (OR) (Cyls Q1Q1 to Q4Q4) (Questa/litho) - Deegam N170.4.1 - S.G specialised XNL20 - Stoneham U61 - Concise NI44

4mm 'SA' phosphor bar right of centre from cylinders Q1Q1, Q2Q2, Q3Q3, Q4Q4 [4.12.90]