Jadeite (also spelled Jadite or Jade-ite, depending on manufacturer) is an opaque, jade-green milk glass that was widely produced for kitchenware and dinnerware in the United States from the 1930s through the 1970s. Named for its resemblance to the semi-precious stone of the same name, jadeite was manufactured by three principal American glass companies—Anchor Hocking, under its Fire-King brand, McKee Glass, and Jeannette Glass—each of which used a distinct spelling and formulation. A closely related opaque blue milk glass, marketed as Delphite by Jeannette and Azur-ite by Anchor Hocking, was produced alongside it. Jadeite was sold cheaply through grocery stores, hardware stores, and five-and-dime shops, and was frequently distributed as a promotional premium with the purchase of flour, oatmeal, or gasoline. Although production had largely ended by the 1970s, jadeite experienced a dramatic resurgence in collector interest beginning in the 1990s, driven in large part by Martha Stewart's public display of her own collection, and the color remains in production today by both heritage American glassmakers and overseas manufacturers.

The use of jade-colored opaque glass for tableware predates the Great Depression; light jade-toned pressed glass was produced by various American manufacturers in the late nineteenth and early twentieth centuries, a category sometimes referred to by modern collectors as Early American Pattern Glass (EAPG) jadeite. The opaque green milk glass that defines the modern jadeite category, however, originated with the McKee Glass Company in 1930, when it introduced kitchenware in a color it marketed as "Skokie Green." The Jeannette Glass Company, also based in Jeannette, Pennsylvania, followed in 1932 with a similar product line, coining the term "Jadite" for its own opaque green glass—a name that, along with its variant spellings "Jadeite" and "Jade-ite," is still used somewhat interchangeably by collectors today, even though each historic manufacturer used its own distinct spelling.

Anchor Hocking, through its Fire-King ovenware brand, did not introduce jadeite-colored glassware until the mid-1940s, more than a decade after McKee and Jeannette, and called its version "Jade-ite," with a hyphen. The color's chemical composition differs subtly across manufacturers and even across individual production batches; because the formula was never standardized, pieces vary somewhat in hue, from pale seafoam to a deeper, more saturated green.

A related opaque blue milk glass was produced alongside jadeite by two of the three principal manufacturers. Jeannette marketed its version as "Delphite" (sometimes rendered "Delfite"), while Anchor Hocking's equivalent, introduced later, was called "Azur-ite." Collectors generally treat Delphite and Azur-ite as closely related but separate categories from jadeite proper.

Anchor Hocking, through its Fire-King ovenware brand, became the most prolific and best-known producer of jadeite, despite being the last of the three principal manufacturers to enter the market. The company was formed in 1937 from the merger of the Hocking Glass Company and the Anchor Cap and Closure Corporation. Anchor Hocking introduced its first Fire-King Jade-ite dinnerware pattern, Alice, in 1945; the pattern was distributed as a promotional premium packed inside oatmeal boxes.

Anchor Hocking's Jade-ite color, like its competitors', was achieved by adding green glass cullet to a milk glass base, producing the characteristic batch-to-batch color variation collectors use to help date individual pieces. Critically, however, civilian uranium use was heavily restricted in the United States between 1942 and 1958 due to wartime and Cold War-era military demand; because Fire-King's production began after this restriction took effect, Fire-King Jade-ite contains no uranium and does not fluoresce under ultraviolet light, unlike the pre-war Jadite produced by McKee and Jeannette.

Anchor Hocking's Jade-ite line eventually encompassed a far broader range of dinnerware patterns than either of its competitors had attempted, including Restaurant Ware (a heavy, undecorated line marketed to diners, hospitals, and other commercial food-service establishments beginning around 1948), Jane Ray, Charm (the only square-format Jade-ite pattern), Sheaves of Wheat, and Shell. Anchor Hocking's Jade-ite sold more than 25 million pieces within its first six years of production and became, by the company's own account, its single best-selling product line. Restaurant Ware in particular became so closely associated with mid-century American diners that the color and the diner aesthetic are now largely inseparable in the popular imagination of the period.

Anchor Hocking also produced a pale blue counterpart it called "Azur-ite," analogous to Jeannette's earlier Delphite, though the two were never made by the same company and are not identical in either hue or composition.