Karpoora Cinthamani Mathirai (KCM) is a traditional Siddha medicinal preparation using to treat Arthritis associated with fever narrated in the text Anubhoga Vaithiya Navaneetham. This formulation has the detoxified ingredients such as Hydrargyrum subchloride and Croton tiglium seeds. The aim was to establish a fingerprint to ensure the quality and safety of KCM. Physicochemical characterization of KCM was carried out using qualitative biochemical analysis and modern techniques such as Fourier transform infra-red spectroscopy, inductively coupled plasma analysis and scanning electron microscopy. Physical evaluation revealed that KCM is a light green colour pill, neutral nature and having solubility in water and HCl with stabilized particle size distribution of 3μ. A clearly identifiable fraction of KCM particles were below 50 nm. The presence of nano sized particles and functional groups carboxylic acids and nitrocompounds in KCM might impart the therapeutic property. Trace elemental analysis of KCM revealed that heavy metals like arsenic, cadmium, mercury and lead were below the deduction limit. Further, elemental analysis of KCM revealed the presence of minerals like calcium, iron, potassium, sodium, and phosphorus under acceptable limits at the prescribed dose of KCM.