As it is a cross, I doubt any Orthodox priest would mind. Don't get too tied up in all the 'magical protection' nonsense, though. Any protection that comes from wearing it would come from faith in Christ, not from the 'talisman' itself. A lot of the 'Old Countries' have Orthodox laiety who think that local superstitions are every bit as valid as the faith. Take my own experience with my Romanian mother-in-law, for instance, when my son was born not only did she say he should stay in the house until he was baptised (for protection) but that he should wear something red to ward off 'deochi' (sort of a curse or the evil eye) that envious strangers might put on him. Both seem like superstitions to me, and the latter sounds frankly pagan. I laughed and ignored it. My wife did the same intellectually but was a little uneasy about it - these superstitions run deep.