In your trading at eBay, the more informed you are regarding an item, the better. Third-party expertise, such as grading, authentication, verification, and appraisal services can provide a second opinion on an item. With these services, you can have another source of information to help you evaluate an item and make your trading decisions on eBay.

• Grading is a way of determining the physical condition of an item, such as "poor quality" or "mint condition." The actual grading system is dependent on the type of item being graded. Different items have different grading systems; for example, trading cards are graded from A1 to F1 while coins are graded from poor to perfect uncirculated.
  

• Authentication is a way of determining whether an item is genuine and described appropriately. Authentication is very difficult because it relies on the expertise of the authenticators. Because of their training and experience, experts can often easily detect counterfeits from subtle details. However, two expert authenticators may differ on the authenticity of the same item.
  

• Verification is a way of confirming the identity and evaluating the condition of an item. Third parties will evaluate and identify an item through a variety of means. For example, some collectors have their item DNA tagged for identification purposes. This provides a way of tracking an item if it changes ownership in the future.
  

• Appraisal services are ways of estimating the value of an item. Appraisers use a variety of methods to appraise items, including expert assessment of the authenticity and condition, and reviewing what comparable items have sold for in the market place in recent months. An appraised value is usually accurate at the time of appraisal but may change over time as the item becomes more or less popular in the market place.

Before you take the advice from these services as the absolute truth, be sure to cross-check these third party opinions to verify the validity of the opinions.