The modern glass term filigrana refers to glass canes wherein one or more colors appear in helical form around a cane of different color. Many writers simply call this "cable decoration." The decorative cane may be made in different ways: 1) two or more different canes joined by heating, then drawn and twisted while still soft; or 2) a drawn cane wrapped or trailed with threads of one or more different colors.
Examples A and B here are wound beads, on which short pieces of cane were laid and trailed threads added, then well marvered so the decorations are flush with the rest of the bead. Here the canes' white threads appear wrapped around transparent glass, rather than suspended within the cane. It is possible that some transparent glass has weathered or worn away, so the present appearance may not be as originally made.
Example C was made quite differently, although the cane that has the red and yellow threads appears also to have had the colored threads wrapped around a more transparent glass that is now quite degraded. This bead was constructed as a "rolled pad," the striped cane pieces and the double-helix cane prepared before a strip of the combination was rolled around a mandrel, the strip's ends fused, and the perforation ends somewhat rounded.
Examples A and B may have been made circa 100 CE, with the possibility that they were made a few centuries earlier -- or later. An example similar to B is depicted in the Greater Washington Bead Society's "Bead Timeline of History" together with beads made perhaps about 100 BCE, but that bead is not discussed in the accompanying publication (James W. Lankton et al., A Bead Timeline, Volume 1: Prehistory to 1200 CE; Washington, DC: Bead Society of Greater Washington, 2004, fig. 6.6, p. 56 and fig. 6.0, p. 53, in group number 602). The same bead seems to have been photographed also in a different group (between numbers 39 and 40) in the Timeline placed in a time period roughly around 900 CE. The group is categorized in "Europe," but no comment is offered for the group or for this bead (Timeline fig. 8.0, p. 74).
Example C is hard to judge, but could have been made about the 8th century CE or even later. Some beads with such decoration have been found in northern European Frankish sites.
The Corning Museum of Glass, Corning, New York, has several beads with such cane decoration around their equators (Acc. no. 72.1.22A-D). They are large oblate spheroids. Three are opaque white glass with undulating trailing of translucent turquoise glass, the additional trailed cane being turquoise glass spirally wound with yellow glass. A fourth is said to have been core-formed, translucent turquoise glass with an undulating opaque white trail, the added cane of white, spiral-wound with yellow glass. Size given is 3.3 cm x 2.6 cm. The beads are attributed to northwest Iran, ca. 6th to 1st centuries BCE, Achaemenid or Parthian periods (Sidney M. Goldstein, Pre-Roman and Early Roman Glass in The Corning Museum of Glass; Corning, NY: The Corning Museum of Glass, 1979, catalog nos. 232-235, beads A, B, C, D, pp. 114-115).
Some beads decorated with such helical-thread or "cable" decoration have been found in England, and a few in Ireland, in sites securely datable at various times between 100 BCE and 100 CE. There is some evidence from distribution of find sites that the beads were made in England, although the origins of the glass components are not certain and workshops not found. These beads are discussed by Margaret Guido in The Glass Beads of the Prehistoric and Roman Periods in Britain and Ireland (London, UK: The Society of Antiquaries of London, 1978), pp. 76-79, 182-187. The cables inventoried as bead decorations are all strictly two-color. The bead forms are annular and oblate spheroids as well as fragments. In the annular examples the cables are often wound around the bead body parallel to the perforation.
Guido also inventories one annular bead, "Translucent light greenish bottle-glass with opaque white around perforation and circumferential bands of finely twisted white, red and blue." The bead, 2.5 cm in diameter, 1.1 cm long, with perforation diameter 1 cm., was found in excavation of the Roman fort (called Arbeia) on the Tyne River, South Shields, Durham. The fort was occupied circa 122-369 CE. At times Spanish, Palmyrene and Tigris elements had been at the fort (op. cit. p. 232, drawing p. 101, fig. 38, no. 10). It is possible that the bands are not whole canes marvered in, but are segments of cane; the drawing depicts four narrow bands side-by-side, with surface color-alternation in diagonal stripes placed so that the directions alternate, chevron-fashion, similar to the effect of spheroid beads made later at Fustat, Egypt as well as probably elsewhere. In the latter, the cane segments are fused aligned with the direction of the perforation, not placed circumferentialy. In the Durham bead, the individual bands appear to be each about 1.5 mm wide or less, narrower than the Fustat-type cane segments. This bead is located in the South Shields Museum.
Some beads with such decoration, the 'cables' opaque white and translucent blue, have been found in early Christian sites in Ireland, circa 8th century CE (Julian Henderson, "An Archaeological and Scientific Study of 47 Glass Beads," in David Freke, ed., Excavations on St Patrick's Isle, Peel, Isle of Man 1982-88; Liverpool, UK: Liverpool University Press, 2002, p. 356). One similar to the Irish type was found in a circa 10th century, CE burial at Peel in a group that probably constituted a necklace, with disparate types of glass and probably varying ages (see discussion by Henderson, and inventory of the beads found in "Beads: Context and Catalogue," ibid., pp. 339-348).
It should be borne in mind that the Canaanite-Phoenicians had traded in England for tin, some centuries before the Roman invasion, and may have introduced some design inspiration, glass-working technology and even prepared glass. Both moving populations and trade, beginning well before the Roman era, may have moved glass, prepared canes, and beads with such decoration into the British Isles from places as far-flung as the eastern Mediterranean basin and northern and eastern Europe.
Bead A here is 12 x 10 mm, B is 11 x 12 mm, and C is 13 x 10 mm (diameter x length through the perforation).
Given the very small scale of these decorative canes, they could not have been drawn after the helical threads were added. Those in the Corning Museum examples cited above appear to be about 3 to 4 mm in diameter. Those in examples A and B here are about 4 mm. diam., and in C about 2.1 mm diameter. The process of marvering those in A and B would have somewhat flattened and broadened the decorative canes. Since these appear to be smaller in scale than those used in glass vessels of the Roman Empire era, they may have been made specifically for decoration of small objects such as beads.
Archaeologically excavated workshops have not been reported that could document when and where such canes were made.
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