Weigh the phone in hand. For comparison, take a similar model, which you are sure. Chinese phones usually weigh much less than their European counterparts.
View Russian menu in your phone. If it is Chinese, you'll know it's a bad translation of all instructions into Russian.
If you have access to the Internet, find out the IMEI number of the phone. For this, type it a combination *#06#. Display will show serial number. Roll it into a string denotes the entry on the website check Click analyse and get all the information about your phone, including the country of origin.