The main device (symbol) in the Chatham blazon is the cross flory. 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.
No other symbol appearing in heraldry is subject to as much variation as the cross 6Boutell’s Heraldry, J.P. Brooke-Little, Warne, (revised Edition) London 1970, P 47. Mediaeval Europe was a deeply religious and Christian and many of the nobility wanted to show their devotion by adopting the symbol of the cross as part of the arms. Since no two arms could be identical there arose many variants of the cross, typically involving patterning along the edges 7Understanding Signs & Symbols – Heraldry, S. Oliver & G. Croton, Quantum, London, 2013, P67, or fanciful, decorative endings to the arms of the cross 8A Complete Guide to Heraldry, A.C. Fox-Davies, Bonanza (re-print of 1909 Edition), New York, 1978, P128. The cross flory is typical of these, having each arm end in something very similar to the fleur-de-lys.