Rare & Hard-To-Find Pyrex

"Rare" and "HTF" (Hard-To-Find) are buzzwords often seen in online listings for vintage (and sometimes not-so-vintage) Pyrex opal ware. Sometimes it's true, but more-often-than-not is not. But what actually constitutes rarity?

Unusual Pyrex -- that which was not standard production-- is by definition also rare. But there are several factors that can make even standard production Pyrex rare and hard-to-find.

One would expect most promotional pieces to be somewhat rare. After all, they were each only produced for short periods, were designed for seasonal gift giving, and were intended to be withdrawn from sale once the promotional period ended (not always the case). But, while some still appear plentiful, others are infrequently seen and command high prices when they are.

Perhaps it is related to the level of demand at the time they were new. Since each season's offerings usually included items at a variety of price points, fewer units of the more expensive promos may have been sold.

Or maybe a design was not as well-received as Corning marketers would have hoped, resulting in lower sales of it.

Both scenarios would result in fewer such pieces circulating in today's collectibles market.

Among the standard patterns, age and longevity appear key to rarity, either alone or in combination.

An older pattern from the late 1950s only produced for a few years would likely have fewer pieces surviving today than, say, a pattern marketed three to five or more years in the 1970s.

Rarity can be a result of market exclusivity. Trading stamp redemption programs offered standard versions of Pyrex patterns, but also featured patterns and color variations of standard patterns exclusive to those channels. Individual bowls not a part of standard sets were seen included, such as the Butterprint 4-quart nesting bowl, added to create a 400 set not available from regular retail venues.

Rarity might also be driven by changes in marketing strategy. A prime example is the high prices seen commanded by Autumn Harvest #500 refrigerator sets. Autumn Harvest debuted in 1979 and ran through 1986, when Pyrex opal ware was discontinued altogether. The refrigerator sets, however, were dropped after 1980, when a clear glass #5000 set was introduced.

Sometimes, a short product lifespan may cause a degree of rarity but one that doesn't necessarily translate to higher collectible value. Oblong casseroles and the Terra pattern are two examples that come to mind.

Conversely, values for the #664 "Big Bertha" round casseroles and the #330 bakeware sets made to go with various early-1970s patterns appear to have benefited from their short lifespans.

The main take away here is that simply because a Pyrex item is described as rare or HTF doesn't necessarily make it so.