Ring – Tourmaline & Diamond Cluster
A modern ring styled as a cross-over cluster principally featuring a claw-set oval tourmaline and 46 round brilliant-cut diamonds pave-set in the shoulders and as the cluster. Entirely constructed from 18ct white gold. Circa 2010.
Assessment of the Tourmaline¹.
Cut: oval mixed-cut (ten-main brilliant-cut crown with a Portuguese-cut² pavilion).
Measuring: 8.13mm x 6.09mm x 4.47mm.
Weight (stone weighed prior to setting): 1.48cts.
Colour: light bluish green (2.5BG.6/7).
Assessment of the Diamonds.
Averages stated where applicable.
18 measuring: 1.30mm.
28 graduating: 1.00mm to 1.30mm.
Estimated total weight: 0.41cts.
Details of the Setting.
Hallmarked: 18ct gold, London, with Emagold solar mark³.
Sponsor’s mark: ‘DOM’ (Domino Jewellery⁴, Vyse Street, Birmingham).
Finger size M.
¹. “Nature creates many wonders, not least amongst gemstones. Tourmaline is one of these wonders; an incredible gem that reflects all the beautiful colours of nature in one group-its name derived from the Sinhalese 'tura mali' which means stone of mixed colours. Tourmaline is mostly found in elongated three or even six sided prisms, strongly striated along the length of its beautiful crystals, which are often multicoloured. It occurs on every continent but the most important gem localities are Brazil, Afghanistan, Myanmar, Sri Lanka, Pakistan, Madagascar, Mozambique, Malawi, Kenya, Namibian, Tanzania, Nigeria, Russia and the USA. It is an exceptional gemstone that displays both piezoelectric and pyroelectric properties. when the Dutch first imported it into Europe from Sri Lanka in the 17th century they used to pull the ash out of their pipes, nicknaming it 'Aschentrekket'. Some of its most stunning colours of the pinks to red is called Rubilite. Others are bright yellow with a touch of green called canary tourmaline; indicolite, which displays the beautiful teal dark blues of the ocean; the green varieties verdelite and chrome tourmaline, and the Paraíba tourmaline, named after the province in Brazil where it was first found, which displays fantastic neon turquoise blues and greens. Then too there are the multicoloured varieties, the watermelon tourmaline in pink and green like the fruit or the more mysterious pink with a clear blue rim. Tourmaline displays an exciting pleochroism, with diverse colours seen in the stone being viewed from different angles-like a kaleidoscope-so the cutter must take great care when faceting to get the best colour results. Each tourmaline is unique, and a fine one is rare, definitely a collector's stone. How could two tourmalines be alike when they display so many different colours and combinations?” (Vladyslav Y. Yavorskyy, ‘Gemstones’, 2017). “Tourmaline is one of the more scientifically interesting minerals, and as a gemstone surpasses all others by its range of colour. The chemical composition of tourmaline is extremely complex. A general formula can be written as WX³Y⁶B³Si⁶O²⁷(O,OH,F)⁴. Where W is sodium, calcium, or potassium; X is manganese, aluminium, ferris or ferric iron, lithium, aluminium, or manganese; and white is aluminium, ferric iron, chromium, or vanadium. Tourmaline is a common occurrence in more siliceous igneous rocks such as granite and granitic pegmatites, and metamorphic gneisses, schists, granulates and similar rocks. The mineral occurs in zones of contact metamorphosis as a result of fumarole action by the mineralising effect of hot gases in the fluid magma” (Robert Webster, ‘Gems. Their Sources, Descriptions and Identification’, fifth edition, 1994).
². A ‘Portuguese-cut’ is a name given to a multifacet brilliant-cut usually employed on elliptical outlines such as ovals and cushions. The design modifies a brilliant-cut pattern by adding additional rows of kite-shaped main facets on the pavilion (and/or crown) which decrease in size towards the major apex (the culet or keel on the pavilion, or the upper star facets of the crown). This has the tendency to improve scintillation, due to the increased number of facets and light performance in general. This facet pattern is the most complex, time consuming and challenging design commonly observed in commercial coloured gemstone cutting. The derivation of the name is uncertain, but probably came into use when Portuguese commercial traders brought South American gem material to Europe in the 15th and 16th century.
³. The Emagold ‘Solar’ mark was an additional hallmark used between 1992 and August 2010 to indicate that the manufacturer adhered to stringent quality control processes when casting. The system was overseen by Emagold (The European Manufacturers’ Association) with the support of the World Gold Council. The Emagold ‘Solar’ mark – a sun-like symbol stamped onto 18ct and 22ct jewellery alongside the hallmark was used to indicate that the manufacturer adhered to the very highest level of quality standards. The scheme was abandoned in August 2010 after the World Gold Council withdrew support. The UK members were Centre Jewellery, Cookson Precious Metals, Curteis, Domino, Euro Findings, The GW Group, Hean Studio, Saunders Shepherd and Stubbs & Co.
⁴. Domino Jewellery, established 1983, is based in Birmingham's Jewellery Quarter, with a trade counter in London's Hatton Garden, who as well as manufacturing jewellery, also supply speciality components to other manufacturing jewellers. Originally a family run business, Domino have now become part of the Heimerle + Meule Group. They are an accredited member of the Responsible Jewellery Council, and guarantee that they provide jewellery with the highest possible ethical credentials with materials that are accountable and traceable. As well as supplying traditional jewellery ranges, they also design and produce in house many award winning contemporary and innovative designs.