The main device (symbol) in the Keel blazon is the crescent. The two main tinctures (colors) are sable and argent.
Sable, the deep black so often found in Heraldry is believed to named from an animal of the marten family know in the middle ages as a Sabellinœ and noted for its very black fur 1A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1894, Entry:Sable. In engravings, when colors cannot be shown it is represented as closely spaced horizontal and vertical lines, and appropriately is thus the darkest form of hatching, as this method is known 2Boutell’s Heraldry, J.P. Brooke-Little, Warne, (revised Edition) London 1970, P 26. Although it may seem a sombre tone, and does indeed sometimes denote grief, it is more commonly said to represent Constancy 3The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P35.
Argent is the heraldic metal Silver and is usually shown as very pure white. It is also known more poetically as pearl, moon (or luna) 4Understanding Signs & Symbols – Heraldry, S. Oliver & G. Croton, Quantum, London, 2013, P53. In a sketch or drawing it is represented by plain, unmarked paper 5A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1847, P11.
For easy recognition of the items on a coat of arms, and hence the quick identification of the owner, bold simple shapes are best. Hence, simple geometric shapes are often used for this purpose 6A Complete Guide to Heraldry, A.C. Fox-Davies, Bonanza (re-print of 1909 Edition), New York, 1978, P146xz`, and the crescent Is a typical example of this, and can appear in any of the main heraldic tinctures. Some common is this device that there are special names for its appearance in various orientations – whilst it lies normally with points upward, the decrescent points to the sinister side, and the increscent to the dexter 7A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1894, Entry:Moon. The allusion, obviously is to the shape of the moon in the sky (indeed, the French have a version “figuré” which includes a face!) and has been said to signify both “honour by the sovereign” and “hope of greater glory” 8The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P106.