Pyrex Collector Forums

I'm cleaning out my grandmother's house. I have a factory sealed box Pyrex mixing bowl set.
Verde green, #300-16, 1-1/2 pt; 1-1/2 qt; 2-1/2 qt.
Box has a price printed on it of $2.95 (!)
It has been sitting in her attic for years. I will assume it was a duplicate so she stored it away.

My question is---I'm putting the item up for sale. Should I leave it sealed or should I open it so buyers can see the items are intact and original?

As strange as it may seem, leaving it sealed in box will have higher value than if you open it. Not to say astronomically higher value, but higher. As long as shaking the box indicates no breakage, you can confidently describe the condition as "mint". Verde was 1967-72, so not terribly old in Pyrex terms.

Thanks for the info and your opinion!