An appraisal does not indicate the true value of your item. We often meet people who have had an item appraised for a certain value and are surprised when we estimate the sales price to be much lower than the appraisal. If your vase/painting/jewelry/antique is appraised to be worth $1000, shouldn't that be what it sells for?
To understand why an item will sell for much less than an appraised value, it's important to understand what an appraisal actually is. An appraisal is a legal document, based on hours of research that establishes the condition, quality, and history of an item and provides a valuation. The valuation is only good for two things: insurance and distribution of assets (usually in a divorce). One of the considerations an appraiser will make in valuing your item is what it would cost to find and replace that exact item in that exact condition. This doesn't fit the real world of buying and selling collectibles, as often a person will accept a substitute instead. Something that's slightly worse condition, for example.
Don't try and use the appraised value for anything other than insurance purposes. You can expect that your item will sell for a fraction of the appraised value, whether you sell through an estate sale, at an auction, or by advertising online.