This paper deals with an important text written by Al-Tīfashāi (580-651 AH/1184-1253 AD) in his famous book “Aʾzhar al-aʾfkar fī gawaḥīr al-aʾhgar" (=The flowers of thoughts about precious stones). Al-Tīfashāi describes a distinguished method of engraving inscription on coral stone rings by “kḥall Qamr haziq" which means the Glacial acetic acid (CH3COOH). This organic acid is suitable for engraving inscriptions on the surface of coral stone rings.
The author interprets Al-Tīfashāi's text following his practical steps, tools, materials used, and the suitable duration for engraving inscription on coral stone rings using this organic acid.
From the archaeological point of view, dating the first application of this method on coral button rings “seals" is crucial. The author endeavours to date the coral button rings preserved in the Islamic Art Museum of Cairo, and to prove that this organic acid was the engraving method for the inscriptions.
The author proved that engraving inscriptions with organic acid had been applied before using sulphuric acid H2 SO4.
Finding out this method of engraving inscriptions by an organic acid. Dating its application during the early Islamic period presents a new scientific contribution to methods of engraving inscriptions (normal or inverted) on archaeological Islamic objects.