Persian word from Arabic root, Jawaher, meaning jewel.
From old Persian "Gohar" meaning jewel; there is no "G" (pronounced like God and Garden) in Arabic, thus the original "Gohar" being jewel and "Goharie" being jeweller were changed to "Javaher" and "Javaheri" during the sixth and seventh century.
After the Islamic conquest of the Persian Empire, during the reign of the Ummayad dynasty, the Arab conquerors imposed Arabic as the primary language of the subject peoples throughout their empire. Hajjāj ibn Yusuf was not happy with the prevalence of the Persian language in the divan, ordered the official language of the conquered lands to be replaced by Arabic, sometimes by force.
The Islamization of Iran was to yield deep transformations within the cultural, scientific, and political structure of Iran's society: The blossoming of Persian literature, philosophy, medicine and art became major elements of the newly-forming Muslim civilization. Inheriting a heritage of thousands of years of civilization, and being at the "crossroads of the major cultural highways", contributed to Persia emerging as what culminated into the "Islamic Golden Age". During this period, hundreds of scholars and scientists vastly contributed to technology, science and medicine, later influencing the rise of European science during the Renaissance.