Materials & Timelines
The use of brass or bronze in a rosary usually means that the item is at least vintage, and probably antique.
Seeds: In the 19th and early 20th century seeds of the Spina Cristi tree were popular as rosary beads. These are almost never seen in modern rosaries.
Job’s Tears seeds are most often found in antique rosaries, but they occasionally seen in modern rosaries as well, and were especially popular in the 1960s.
Irish Horn rosaries are usually from the 1930s through the 1950s, although crafting small objects out of horn was a national tradition in Ireland from at least the early 1800s. One manufacturer, the Mitchell Rosary Factory of Dublin, appears to have been the source for all the Irish Horn rosaries produced in the 20th century, and possibly even earlier. Mitchell’s stopped making horn rosaries by the 1960s.
Bone was a common bead material prior to the 20th century. Still available but not commonly used; beads made from bone usually indicate an antique rosary.
Rose Petal Beads are a 20th century invention. Despite the appealing notion that rose petal beads are medieval and rosaries were originally made from them, there is no evidence of this. Rose petal beads don't appear in literature or in existing rosaries prior to about 1920.
1590 Milk Glass
White milk glass was first made in Venice in the 16th century, colors were introduced staring in the late 1700s. Colors include blue, pink, yellow, brown, black. 19th-century glass makers usually called milky white opaque glass "bone glass"; the name milk glass is relatively recent. The white color is achieved through the addition of an opacifier such as tin dioxide or bone ash.
Goldstone was invented in 17th century Venice by the Miotti family, who were granted an exclusive license by the Doge. Persistent folklore describes goldstone as an accidental discovery by an unnamed Italian monastic order or medieval alchemists, but this appears to be only a legend.
Antique Goldstone is usually a reddish-brown, containing tiny crystals of metallic copper that require special conditions to form properly. The final appearance of each batch is highly variable; the outer layers tend to have duller colors and a lower degree of glitter. The best material is near the center of the mass, ideally with large, bright metal crystals suspended in a semitransparent glass matrix. Beads are usually carved from this mass, not molded or blown.
By using minerals other than copper, Goldstone can be made in purple, blue, and green – these colors are rare in antiques but common in modern manufacturing.
1800 to 1920 Opaline Glass
A decorative style of glass made 1800 through the early 1900s, though it reached its peak of popularity in the 1850s and 1860s. The glass is opaque or slightly translucent, and usually white, although it can be found in green, blue, pink, black, lavender and yellow. It was made by adding heat-reactive minerals during manufacture, usually Calcium phosphate (bone ash) to make it opaque, and arsenic to create the opalescence.  The primary influences on this style of glass were 16th century Venetian milk glass, and English white glass produced in 18th century Bristol.
The term "Opaline' is used for several different types of glass, including, occasionally, plain Milk Glass.  Here, we are using the term to refer to semi opaque glass with an opal-like internal fire.
1829 Pressed Glass
The first recorded showing of pressed glass beads was in 1829, at a trade show in Prague. By 1850, glass beads were being produced by the millions, and exported all over the world. Pressed glass beads became very popular because of interesting shapes including faceted surfaces.
1850 Camphor Glass
Camphor glass is clear glass that has been treated with hydrofluoric acid vapors to give it a frosted, whitish appearance. This effect resembles gum camphor, hence the name. Camphor glass became popular in the mid 1800s, reaching it peak during the art deco period around 1920/1930. It's still made and used today.
1850 to 1915 Saphiret
Made in Gblonz, Bohemia (Czechoslovakia) in the mid 1800s through around 1915, Saphiret is highly collectable. Made by mixing colloidal gold into sapphire-colored glass, resulting in a pale plum to brick red glass that reflects a saphire blue surface. Often found in brass or gold-filled settings, as this was ‘only’ glass. A similar glass was briefly produced in the mid-1900, but it lacked the luster of antique Saphiret and was discontinued.
1860 to 1955 Prosser Ceramic Glass
The "Prosser" technique of pressing glass, invented in 1840, consists of molding a cold glass and ceramic paste under great pressure and then firing it. The finished product looks like porcelain and is often referred to as such. This method allows for only opaque colors, not fully transparent ones. In 1844 Jean-Félix Bapterosses patented a machine for making buttons using the Prosser method - he also improved the plasticity of the glass paste by incorporating milk into it. Bapterosses started producing beads in 1860 - 1864. All Prosser beads have a seam running around the bead.
1895 Swarovski Crystal
In 1892, Daniel Swarovski invented a machine that revolutionized the process of cutting crystal. The Swarovski company was founded in 1895.
1950 Aurora Borealis Finish
The Aurora Borealis crystal finish was created in collaboration with Christian Dior in 1950. Widely available after 1955, this was the first of many metal-based finishes created by Swarovski for their crystal beads. Wildly popular in the 1950s and 1960s, and still in use.
AB is a finish on about half of the crystal. AB-2X covers the entire crystal.
1843 to 1900 Vulcanite, Ebonite
Vulcanite is a combination of vulcanized rubber and sulfur, a material invented in 1843 by Thomas Hancock and used extensively in jewelry, combs, and buttons. It was particularly fashionable for mourning jewelry in the late Victorian era (1860-1900) after being popularized by Queen Victoria.
1843 Gutta Percha
A hard rubber-based material that looks like wood, introduced in 1843. While still in production for use in dentistry, Gutta Percha hasn't been used for beads since the mid 20th century.
1855 to 1926 Bois Durci
Made from a paste of fine sawdust and an organic binder such as egg white or blood, molded under high pressure and steam heat. Patented in Paris in 1855 by the Parisian writer Francois Lepage. Hard and highly polished, it was used as a wood substitute or to mimic jet, bone, or metal. Sometimes used to create religious medals that look very similar to bronze. (1)
1869 to 1940 Celluloid
Celluloid was introduced in 1862 as Parkesine, an artificial ivory. Popular into the first half of the 20th century. Beads were made of celluloid starting in about 1900 and were very popular during the Art Deco period. Celluloid is unstable and prone to significant changes with age; it may yellow with time, turn pinkish-brown, warp, or crumble. It's flammable and softens when exposed to mild heat.
1900 to 1980 Casein
Casein was first exhibited at the Paris Exposition of 1900 under the trade name Galalith. Under the name Erinoid, casein was exhibited at the first British Industries Fair in 1915, and an improved version was patented in 1950. Casein manufacturing continued until about 1980.
Casein plastic is made from chemically-hardened milk proteins, and does not melt into a liquid. Casein was usually manufactured in sheets and then mechanically stamped out in basic shapes, which were hand tooled into the finished objects. It can be dyed almost any color, or combination of colors, and often was used to imitate ivory, horn, or tortoise shell.
Casein can lose moisture over time, and sometimes you can see this as a subtle "crinkle" on the surface.
1909 Bakelite, Catalin (Phenolics)
A heavy and dense plastic material. The first truly synthetic plastic.
As bakelite and catalin age, UV light causes a layer of phenyl alcohol to form on its surface. Phenyl alcohol is yellow-brown, so it imparts that tint to the original color. Thus cobalt becomes "blue moon" to olive green (see photo below), bright red becomes mahogany, white becomes butterscotch. Phenyl alcohol is an excellent sunscreen, so the discoloration only penetrates a millimeter or so. These plastics are very resistant to chemicals, and will never melt or ignite. Catalin, however, will shrink over time. This can result in warping and cracking of the piece.
1933 Lucite, Acrylic
A common bead material from the 1930s onward. Early Lucite was not considered a cheap material, and can be found in rosaries with sterling crosses and centers.
1823 Alpacca (Alpaca, Nickel Silver, German Silver, Chinese Silver, New Silver)
Looking nearly identical with silver, Alpacca has no silver content and is an alloy of copper, nickel and zinc. It is also known as nickel silver.
In 1770 German metalworks were able to produce a copper-nickel-zinc alloy for the first time, in imitation of imported "Chinese silver". In 1823 the process was perfected independently in both Germany and England, and the trademarked name Alpacca became widely used. Widely available after the 1860s.
Aluminum was introduced in 1827, and was originally an expensive material. Very popular with religious artists from the1880s though the 1920s, because of it's light weight and the way fine detail could be cast, many antique crucifix and medals are aluminum. Aluminum is relatively soft and easily damaged. Still in use today, especially for medals, aluminum is no longer expensive.
Before the mid-19th century, carbon steel was expensive and was only used where no cheaper alternative existed. With the advent of speedier and thriftier production methods, steel began replacing brass and copper for chains and links.
1860 to 1950 Coca, Coco, Taqua (Vegetable Ivory)
Vegetable ivory was a popular material for vintage rosary beads, and is still available, although less common. Often called Coca, Coco, or Tagua, it is not related to the coconut palm. An ivory substitute since at least the mid 19th century, vegetable ivory is beautiful in it's own right. It has a texture and hardness similar to elephant ivory, with a rating of 2.5 on the scale of mineral hardness.
According to legend, a ship sailing from South America to Germany in 1865 carried a load of tagua nuts as ballast. Upon arriving at dockside in Hamburg, curious stevedores began playing with the taguas, and, noticing their ivory-like characteristics, began using it for scrimshaw.
Ivory nuts were a popular material for buttons, beads and small sculptures until the 1950s, when plastics greatly reduced the demand for tagua nuts.
Several tropical palms produce vegetable ivory. Phytelephas aequatorialis, also known as the ivory-nut palm, grows along the banks of tropical American rivers from Panama and Colombia to Peru. Metroxylon amicorum, the Caroline ivory-nut palm, is native to the Caroline Islands of Micronesia. Hyphaene ventricosa is an African palm native to islands and banks of the Zambezi River near Victoria Falls.