GlobalGemology

Here is an additional photo of the obverse:

Good morning, I'm currently appraising a large coin and currency collection but must admit I am not well versed in Russian coins. I've attached a photo of twelve 1899 Russian 10 Rouble gold coins. However, I have a suspicion that they may be counterfeit. I'd greatly appreciate any information you may have to offer. Here are the approximate specs of each coin, which is very consistant: Diameter: 22.9mm Thickness: 2.17mm Gross Weight: 7 grams From what I've read, the diameter and thickness are supposed to be 22.5mm and 2.15mm. I'm not sure if this variance is large enough to be concerned about. However, I believe the gross weight is supposed to be 8.6 grams and these only weigh 7 grams, which does set off a red flag for me. Also, there is some green oxidation on several of the coins, which I'm assuming is due to the composition not being gold. Thanks again for your help. Sincerely, Scott