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| Monday, 20 October 2003 |
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Sapphires of Sri Lanka by T. Piyadasa, Director General, National Gem & Jewellery Authority Sri Lanka has already got a national flag, national anthem, national tree and a national flower. Cabinet has given approval for adoption of the blue sapphire as a National Gemstone of Sri Lanka, and to issue a stamp with the picture of the blue sapphire concurrently so as to give publicity to this initiative. The stamp is released as the National Gem Blue Sapphire and also commemorate the certification date (21.10.1993) of National Gem and Jewellery Authority Act.
Pure Corundum is colourless. In hardness corundum is second only to diamond and rates 9 on Moh's scale. The red variety is termed 'Ruby'. Blue corundum is called 'Blue Sapphire'. All the other colours except 'Pathmaraga' are simply termed with colour designating prefix such as Yellow Sapphire, Pink Sapphire and Green Sapphire. Corundum is Aluminium Oxide (Al2O3). The colour in rubies could be in various shapes and is dependent on the quantity of chromic oxide present. The colour in ruby could be patchy banded or uniform. The colouring oxides responsible for the Blue Sapphire are the Iron and Titanium. A remarkable improvement in colour and lustre is shown in the course of polishing in 'Rambuka' Blue Sapphires of Sri Lanka. Iron is basically the colouring element in Yellow Sapphires.
They are identified as Pushparaga. Most reputed area is Aluthnuwara in Balangoda electorate. The term Pathmaraga is a Sinhalese term applied to very special colour variety of corundum. This word in Sinhalese language means colour of 'Lotus flower'. The name Pathmaraga is now universally accepted. The colour of this stone is a combination of yellow, pink and orange. This mineral is a member of trigonal crystal system. Asteriated Sapphires are in blue colour known as Star Sapphire. If these asteriated sapphires are in red colour, they are known as Star Rubies. When such stones are cut 'en cabochon', they display a special reflection effect in the form of six and in rare instances a twelve rayed star on the cabochon surface. This star effect is shown in yellow colour stones of corundum family. Zircon is one of the most common solid inclusions found in Sri Lanka Corundums. These are rounded grains of Zircon surrounded by tiny tension fractures creating a halo. (Zircon haloes). Other common mineral guests in Sri Lankan sapphires are dark prism of rutile, hexagonal prisms of apatite and spinel octahedra. As with all gems, the value of corundum gems depend on colour, clarity, weight and the quality of cutting. Flawless, transparent blue sapphires of deep colour are highly prized. Sri Lanka's Blue Sapphires stand out in any collection of the world's best gemstones.
It is also necessary to mention Sri Lanka Geuda Corundum. Approximately 85 per cent found in Sri Lanka are 'Geuda'. Geuda is low gem quality corundum. These varieties can be turned into high quality Blue, Yellow Sapphire by heat treatment. Generally gemstones containing geuda display a smoky, milky or murky appearance. They are semi-transparent, semi-translucent, whitish or semi-brownish milky or silky corundum with characteristic 'diesel effect' (colour of diesel fuel) in transmitted light. This effect or cloudiness is caused by the presence of a dense concentration of rutile. (T102) inclusions. According to the symposium classification four main sub-varieties are identified. These names were common usage in the trade. What symposium did was to categorise and separately identify the, numerous varieties according to their properties as follows: i. Diesel Geuda ii. Silky Geuda iii. Ottu Geuda iv. Dun Geuda Classification of 'Geuda' is as follows: (i) Geuda - Diesel Geuda; Milky Geuda; Silky, Milky Geuda' Young Milky. (ii) Ottu - Pita Ottu - Dot/Dun/Iri/Ural/Black; Atul Ottu - Dot/Dun/Iri/Ural/Black. (iii) Silky - Silky; Young Silky; Thick Silky. Sri Lanka is considered one of the oldest sources of sapphires. No sapphire in the world can equal that obtained in Sri Lanka. Dr. Gubelin, the famous Gemmologist with his vast knowledge and experience recognises a blue sapphire from Sri Lanka. He decides this by the study of inclusions which are in themselves typical. Good Blue Sapphires from Sri Lanka are reputed for having a very pleasing intensity of colour. Its degree of transparency is very high. Clarity is excellent. These characters combined enable the stone to display a very high lustre. Legend says King Solomon in the Biblical times wooed the queen of Sheba with precious stones from the paradise isle. Marco Polo the supreme traveller who had seen the wonders, mysteries and the unparalleled splendour of the Kingdom of the Cathay, was amazed by the priceless Ruby in the possession of the King of Sri Lanka. He recorded his wonder in these words, "It was a span in Length, without a flaw, brilliant beyond comparison." Richerd W. Huges, author of 'Ruby and Sapphire" book says abut a sapphire of 2965 cts. fist sized example and was estimated to yield a number of cut gems in the 50-100 ct. range. But he has not mentioned the details of the exact locality. The biggest Sapphire Gem 563 carats on display at the American Museum of Natural History in New York named as "The Star of India" but in the actual fact, it is from Sri Lanka. Some of the Sri Lanka's most renowned Sapphires: Blue Giant of the Orient, 466 carats - "The Morning Leader" a news paper in Sri Lanka on August 23, 1907 published the following news item under the headline "A moonstone Sapphire worth 7000 pounds". The stone was mined in Ratnapura district some six months ago. In its finished state it is 2 1/2 inches long, 1 3/4 broad and its greatest thickness 3/4 of an inch. The Sapphire, there is every reason to believe is the largest sapphire in the world. BBelle of Asia 400 carats - Discovered in the paddy field of Pelmadulla in 1926. Reputed gem dealer sold the above stone to the British named Lord Naffield. The Blue Belle is held in the highest esteem among blue sapphires owing to its highly prized peacock blue colour and its excellent clarity. Blue giant of the Orient 486 carats - Considered to be the largest blue sapphire in the world was sold to a Japanese by a reputed gem dealer in 1972. Now this stone is in Switzerland. Logan Blue Sapphire 423 carats - Considered to be the second largest blue sapphire on record. It is a flawless specimen. A rich deep blue in colour. Gifted to the Smithsonian institute in Washington by Mrs. John A. Logan. Star of Lanka 362 carats - The Star of Lanka has the reputation of being the third largest star sapphire of similar quality in existence. This is rich deep blue in colour and has a well defined six rayed star. This is owned by the National Gem and Jewellery Authority of Sri Lanka. Another star sapphire was found weighing 224 carats named as "Star of Asia". Rosser Reeves Star Ruby 138.7 Carats - The world's largest star ruby of comparably fine quality. It has rare features of excellent colour, a well defined star and good transparency. One of the outstanding gem collection at the U.S. National Gem Collection at the Smithsonian. Recent discoveries of large sapphires 1. Orange Sapphire (825 Carats) - This was found from a gem pit at Kuruwita in Ratnapura district. It was transparent and free of cracks. 2. Blue Sapphire (856 Carats) - This was found in a gem pit at Hakamuwa close to Ratnapura city in 1998. This was named as "Pride of Lanka". 3. Blue Sapphire (8042 Carats) - This was found in a gem pit at Pelmadulla in Ratnapura district. It was named as "Splendour of Lanka". 4. Blue Sapphire (2516 Carats) - This was found in a river bank at Ellawala in Ratnapura district. It was transparent. 5. Blue Sapphire (4002 Carats) - This was found in a gem pit at Neelagama in Ratnapura district in the year 2000. 6. Blue Sapphire (254 carats) - This deep Blue Sapphire was found in a gem pit at Ganegama near Pelmadulla in Ratnapura district. According to the reports received following Blue Sapphires were mined during this year in Ratnapura district. i. 1200 Carat Blue Sapphire - Kosgala. ii. 138 Carat Blue Sapphire - Watapotha. iii. 260 Carat Blue Sapphire - Pelawela. Synthetic Sapphires were introduced in 1902 onwards by various names such as "Vernuil, Chatham, Czocharlski. Then 1980's diffused stones were introduced. Now the threat to the sapphire is known as Bulk diffusion. At present there are stones of corundum family such as blue, green and brown coloured sapphires are also produced by the same way of Beryllium bulks diffusion treatment. This is alarming to all the coloured sapphires. |
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