* Fake cards often use cheaper materials. The silver mark could be from a cheap metallic ink or coating used to imitate the foil found on authentic cards.
* Authentic cards have a specific foil texture. The foil on genuine Yu-Gi-Oh! cards has a textured feel that's difficult to replicate. If the silver mark feels smooth or uneven, it could be a sign of a fake.
* The silver mark shouldn't be easily scratched. Authentic Yu-Gi-Oh! cards have a fairly durable foil layer. If the silver mark is easily scratched off, it's highly likely the card is fake.
Here's what you can do:
1. Compare to Authentic Cards: If you have any genuine Yu-Gi-Oh! cards, compare the foil finish.
2. Check for other Signs of Fakes: Look for inconsistencies in the card's design, print quality, or alignment.
3. Do some online research: Use reputable online resources like the Yu-Gi-Oh! Wiki to verify the authenticity of the specific cards you purchased.
4. Contact the seller: If you suspect your cards are fake, contact the eBay seller and explain your concerns. Be prepared to provide evidence.
Remember: It's always a good idea to be cautious when buying Yu-Gi-Oh! cards online. Make sure you're buying from a reputable seller and inspect the cards carefully before confirming your purchase.