Here is a thread to checkout discussing a cross-grade. It varies on a card by card basis. There is no universal answer that one grade at BGS will result in another at PSA. The higher the grade at one company, the more likely to result in a strong grade at another. A BGS 10 can command more because it offers an evaluation above “gem mint”, the designation given to a BGS 9.5 and PSA 10. Once again, additional value varies by the card and the existence of a buyer who thinks that a card should carry a premium with that designation.