On your right photo the second line of main text in the center gives the name of the caliph, "al-Qadir bi'llah". That's always handy to date the coin roughly as al-Qadir ruled between 991 and 1031AD. I can't clearly read the name of the ruler on the coin. However, the lowest line on one side reads "yamin al-dawla" on the other side "abu l'Qasim " These are some (of many) titles of Ghaznavid ruler Mahmud. He ruled 998-1030AD, nicely fitting with the reference to the caliph on the coin. Can not comment on value. I don't know much about this category. It is impossible to judge a coin like this from on a photo. Unfortunately there are a lot of fakes of these about. This thread might be better at home in the ancients category ?
Yes, it cetainly looks like an Islamic gold dinar from the medieval period. I took the liberty of moving this to the Ancients forum, where it is perhaps more likely to get specialized attention and yield you some information. Kudos to @THCoins for providing an excellent start in that direction.
An interesting Islamic dinar, but the gold alloy might be low in the 11th-12th century. It starts at about $100 if it's real.
The Abbasid reign witnessed a long period of decline, due to political, ethnic and confessional divisions and divergences. The OP coin pertains to the Ghaznavid Dynasty, as stated by brother THC. It's a Turkish Dynasty of Afghanistan and the Punjab, ruling new States east of Baghdad ( 962 - 1186 AD ). The Abbasid Caliphs themselves were under control of such Dynasties which arose during that long decline.. I think IMHO that it's a rare significant and witnessing coin, let the precious metal aside ( being itself rare).
As 7Calbrey stated, the Ghaznavids expanded the Arab world into India. This is nicely witnessed by another coin issued under the rule of Mahmud from Lahore. The text on one side is in Arab, the other side in Indian Nagari script. This was, however, a relatively short lasting experiment. (Goron& Goenka GZ3, AR 19 mm, 2.59 gr, 418 AH)
