“The best things in life are free,” rarely seems to apply these days. “Free Wi-Fi” means first spending $4 on a cup of coffee, and “fat free” usually translates to “flavor free.” But in the 1930s, young women scrounged through containers of Quaker Crystal Wedding Oats for a piece of jadeite tableware. You read it right, collectible glassware in the oatmeal. True, it wasn’t totally free, but 24 cents for a tub of oatmeal and a mug comes pretty darn close.

Once a mere giveaway item, jadeite—named for its opaque, pale-green color—sits at the top of the wish list for many of today’s collectors. Paula has long admired its vintage charm and has recently started a jadeite collection of her own. Coffee mugs and cereal bowls, which she uses for heaping scoops of ice cream, are among Paula’s favorite pieces, but a rare batter bowl given to her at Christmas by Food Editor Libbie Summers holds a place of honor in her heart and her kitchen.

It’s not too difficult to build a jadeite collection like Paula’s because the tableware was mass-produced from the 1930s until the early 70s. Vintage pieces can be found by scouring thrift markets, antique stores and yard sales. But it’s important to know what to look for because companies capitalizing on the current demand for all things retro have saturated the market with reproductions.

One reason why it’s good to know your jadeite history.

The glassware initially came into fashion because it was durable and cheap to produce. McKee was the first to manufacture jadeite, but the Jeannette Glass Company is credited for coining the name. However, Anchor Hocking Glass Corporation became its largest producer. In 1942, Anchor Hocking debuted the popular Fire-King line in a variety of colors, but jadeite (or “Jade-ite” as the company calls it) remained in high demand for 30 years.

The stain- and heat-resistant tableware was served in frugal diners across America. Additionally, restaurant owners could save money by serving coffee in thick-rimmed “cheater mugs” that appeared to hold more than they actually did. The simple design of the Anchor Hocking Restaurant Ware was one of the most popular lines produced from 1950 to 1956. Today, Restaurant Ware is also the most collected, in part because of its sheer abundance.

Collectible jadeite pieces come in many forms and, as usual, the hardest to find items fetch the highest prices. Whereas mugs generally sell for around $20, a Fire-King grease jar can run $100. A set of four nesting bowls in mint condition may sell for $200.

A keen eye can tell the difference between vintage jadeite and department store knock-offs. You can identify the maker (and worth) of most pieces by examining the markings on the underside: “McK” in a small circle indicates McKee, and a “J” inside a triangle indicates Jeannette Glass Co.

However collectible, there’s no reason to store jadeite out of reach. Paula prefers putting her pieces to work rather than letting them collect dust. She uses jadeite tableware to transform her dining table into a colorful and inspired springtime setting.