Educate and familiarise yourself with what makes a real Buddhist relic. Genuine items will all have similar characteristics and be of a reasonable quality. For example, a Buddha amulet, often referred to as a votive amulet is a common item to be reproduced fraudulently due to their relative popularity. These items are made for many reasons, including their high price point. When examining the images of a relic on eBay, looking at the face of an amulet, for example, will be the most telling with regards to its quality. If the colours are not vibrant and the gems lack the lustre you would find in real mined gems, then you should consider the possibility that it might not be a genuine item. Familiarising yourself with the characteristics of the characteristics of true Buddhist relics will make a world of a difference when trying to identify fake items on eBay.
The price is telling
Consider the price of the precious metals, gems etc. used in creating the relic. A good rule of thumb to go by is that if the price of the item seems too good to be true, then it probably is! This tip is especially useful to those who have not got an extensive knowledge of the characteristics of Buddhist items. The age of the item will also have an effect on the price. Older items will have a higher monetary value due to their historic significance. This also speaks to the quality of the item as it has stood the test of time, showing that it was crafted with quality materials, and proper craftsmanship. Many sellers on eBay buy these items with the intention of reselling them at a profit, so markups may be expected.
Check the seller
When you have found an item that appears to be genuine on eBay, click into the profile of the seller and research their reputation. If the seller has a good reputation on the site, then this will be a good indicator of the legitimacy of the items which they are selling. Reputable sellers will also have clear, good quality, high resolution photos of their items they are selling, along with a good and detailed description. If a listing on eBay has poor quality photos, this may be intentional and used as a means of deception. Perhaps, if the photo was of a higher resolution, it would have clear signs that the item was fake. However this may also be an honest mistake from an honest, though inexperienced seller. In these cases, don't be afraid to ask for supplementary pictures of the item. If the seller is selling a genuine item, they will more than likely oblige.
In conclusion, the easiest and most effective way to ensure the items you're purchasing on eBay are true Buddhist items is doing thorough research on the seller, item you wish to purchase and most importantly, use your common sense! If the deal seems too good to be true it probably is.