The short answer: no, you cannot be certain that vintage corelle is lead-free. It’s a little more complicated, though. Corelle is known to produce Vitrelle multilayer glass tableware that is currently lead-free. However, it was not certified lead free until 2005, and dishware produced before then may have very small amounts of lead present, particularly on decorative pieces. The lead amount is likely very small, but still, this means pre-2005 pieces are lead-safe, but likely not lead-free.
You should espeically be wary of bright colors, decorations, and any glaze that looks chipped or worn. It’s best to just eat off of a post-2005 set. This being said, vintage Corelle is likely much safer than other vintage dishware which probably contains much higher amounts of lead and cadmium. To be safe, I wouldn’t use any vintage dishware, period.
