That is a very expensive gift. Was she told the provenance, if not she needs it. A coin like this needs its past sales (& findspot) with it, its present history is as important as its Ancient. These are one of the most copied types of coin, so I would suggest taking it to an expert in ancient coins. If real, she is a very lucky lady, tell her from me.
PS.
Here are a couple of simple tests;
No good provenance - possible red flag
Weigh it (to 0.00 accuracy) - Check its the right weight, if too far out - red flag
Test with a magnet - if sticks - red flag
Check the edge of the coin - if there is a seam - red flag
Check the Die Axis - 12o'c or 6o'c etc (on these coins, not sure what they are meant to be, not something I studied)
If all these check out OK, you may not be out of the woods. They have even made them from real gold without seams etc...