The two main devices (symbols) in the Logan blazon are the nail and heart. The two main tinctures (colors) are gules and or.
Red in heraldry is given the name Gules, sometimes said to be the “martyr’s colour”1The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P36. The colour is also associated with Mars, the red planet, and the zodiacal sign Aries 2Understanding Signs & Symbols – Heraldry, S. Oliver & G. Croton, Quantum, London, 2013, P53. Later heralds of a more poetical nature would sometimes refer to the colour as ruby, after the precious stone.3A Complete Guide to Heraldry, A.C. Fox-Davies, Bonanza (re-print of 1909 Edition), New York, 1978, P77.
Or is the heraldic metal Gold, often shown as a bold, bright yellow colour. It is said to show “Generosity and elevation of the mind” 4The Symbolisms of Heraldry, W. Cecil Wade, George Redway, London, 1898 P35. Later heralds, of a more poetic nature liked to refer to it as Topaz, after the gemstone, and, for obvious reasons associated it with the Sun 5Understanding Signs & Symbols – Heraldry, S. Oliver & G. Croton, Quantum, London, 2013, P53. In drawings without colour it is usually represented by many small dots, or by the letter ‘O’ 6A Complete Guide to Heraldry, A.C. Fox-Davies, Bonanza (re-print of 1909 Edition), New York, 1978, P76-77.
It is important that a coat of arms be easily recognised and so everyday objects were frequently used as clearly identifiable charges – tools 7Boutell’s Heraldry, J.P. Brooke-Little, Warne, (revised Edition) London 1970, P 69 being a common and important example of these, of which the nail is typical. Some of these tools are rather obscure to modern eyes, who of us nowadays would recognise a hemp-break 8A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1847, P163, let alone know what to use it for! Nevertheless, for mediaeval peasant it was a clearly identifiable symbol.
The heart is represented by the conventional symbol that we see today on playing cards. In later arms it can also appear emflamed and crowned. 9A Glossary of Terms used in British Heraldry, J.H. Parker, Oxford, 1894, Entry:Heart Guillim, the 17th century heraldic author, believes that it shows the holder to be a “man of sincerity…who speaks truth from his heart”. 10A Display of Heraldry, J. Guillim, Blome, London, 1679, P184