With real estate it is location,location,location. With china and porcelain, condition, condition, condition. There are some exceptions, where a pattern is extremely rare. Your family may have been using it for years, but the person who is going to buy this, doesn’t want the defects.
So what affects the value.
Small nicks or chips to pieces generally get put into the Goodwill pile unless they are a foot of a tureen or large item, but the value is hugely decreased.
Cracks – if it has been repaired – to the Goodwill pile, It it is hairline crack on a larger piece , but again the value is hugely decreased.
Crazing – These are like the spider web like lines that can appear on porcelain and china. This occurs during manufacturing when the glaze is applied, and during the cooling process the glaze gets slightly cracked. This is very common on older American porcelain, and some Ironstone pieces. You can see an example of crazing to the right. Over time these cracks get oils in them that over time become discolored. Depending on the extent they can severely decrease the value or even put into the donate pile.
So, basically, go through every piece, and put aside all the items with chips and cracks and crazing and see what you have left. The family may have started with a full 12 piece setting of fine china with all the serving pieces, but it is not unusual to only have a true 8 piece setting left.