Ministry of Enterprise Development and Investment Promotion

Colour Balance in Padmaraga

1Presented by Mr.Upali Nandalal GemmologistHistorical background of PadmaragaThe name derives from the Sinhalese word for Lotus blossom, from time to time. It changes as Pathmaraja according to the Sanskrit language.

Pathmaraja, Padmaraga and Padmaradscha are words referred to the same stone.

2Corundum FamilyRuby Blue SapphirePink SapphireYellow SapphireOrange SapphirePadmaragaPurple SapphireGreen SapphireWhite SapphireStar SapphireColour Changing Sapphire

3Properties of Corundum familyChemical composition- Al2O3 (Aluminum Oxide)Crystal System- TrigonalCrystal habit- Barrel shapeHardness- 9.0 (Mohs scale)Specific Gravity - 3.99Refractive Index - 1.762 1.770Birefringence- 0.008Optic sign - Uniaxial (Negative) Cleavage- NoneFracture - Conchoidal, SplinteryLuster - Vitreous Streak - White

4Padmaraja is a Pink Orange Sapphire, originally being mined in Sri Lanka, but also found in Gem deposits of Madagascar, Tanzania and a few in Vietnam and Africa.

Padmaraga (Sapphire) is very Rare and therefore highly valued.

55Behavior of Light rays within Gemstones Singly RefractiveDoubly RefractiveA light ray entering into a Doubly Refractive Gemstone will split into two rays with two different velocities and vibrational directions (Other than parallel to the optic axis). 6As corundum belongs to Doubly Refractive category, light will behave in the same manner.Corundum with a single colour (e.g. :- Blue Sapphire and Ruby) the colour splits into two colours.

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Atomic structure of Corundum (without colouring elements)8

Colourless Corundum (White Sapphire)Pure Aluminum Oxide without colouring elements. Possible sites of Colouring elements. 9

10Pink Sapphire Substitution positions are occupied by Chromium atoms (randomly) [Lesser number of Chromium atoms, which are not enough to create deep red colour of Ruby.]

11Yellow Sapphire

Substitution positions are occupied by Iron atoms (randomly) [further the yellow colour of Sri Lankan Yellow Sapphires is also produced by colour centers].

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Substitution positions are occupied by a lesser number of Chromium atoms and Iron atoms (Colour Centers could also produce yellow colour).Orange Sapphire

13Patchy Orange colouration of Pink Sapphire creates Orangish Pink Sapphire, Which is called Padmaraga Padmaraga

14Yellow SapphireSubstitution positions are occupied by Iron atoms (randomly) [further the yellow colour of Sri Lankan Yellow Sapphires is also produced due to colour centers.

Pink Sapphire Substitution positions are occupied by Chromium atoms (randomly) [Lesser number of Chromium atoms which are not enough to create deep red colour of Ruby.]

Substitution positions are occupied by a lesser number of Chromium atoms and Iron atoms + Colour Centers.Orange Sapphire

Patchy Orange colouration of Pink Sapphire creates Orangish Pink Sapphire, Which is called Padmaraga

Colour distribution of Blue Sapphire Distribution of Blue colour is shown in this picture.

Distribution of Pink and Orange colourations although not commonly visible, it is assumed to be in the same manner.15

Patchy colouration of Padmaraga.Variations of Pink and Orange Colour Intensities. 161. Pink with a low intensity of Orange colouration. Colour is evenly distributed but intensity of Orange is very very low. Therefore the stone can not be classified as Padmaraga

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2. Light Purplish pink with a highly intensed patchy Orange Colouration.Orange Colour is patchy. As the colour patch is located close to the culet, the colour gets dispersed throughout the stone, showing Orangish Pink through the table. Therefore it could be classified as Padmaraga. 18

3. Purplish Pink with low intensity of Orange colouration. Here, Orange colouration is masked by high intensity of Purplish Pink colouration of the stone. Therefore it could not be classified as Padmaraga.19

4. Pinkish Orange PadmaragaBoth Pink and Orange colours are evenly distributed throughout the stone. But intensity of the Orange colour is higher than Pink. It is termed Pinkish Orange Sapphire. If the intensity of Pink colour is higher than orange, it is termed Orangish Pink Sapphire. 20

When both Pink and Orange Colour components are there in equal proportions (50% - 50%), then the stone is termed Pink/Orange Sapphire or Orange/Pink Sapphire. This is the ideal colour balancing of Padmaraga. 21

Colouration of Padmaraga could also vary in following manner.30% Orange + 70% Pink70% Orange + 30% PinkThere could be varying proportions of Pink/Orange colourations which could also be considered as Padmaraga.2230% - 70%70% - 30% 50% - 50%PinkOrange (Orangish Pink)(Ideal colour of Padmaraga)(Pinkish Orange)Pink prominent Padmaraga is preferred by Japanese buyers.

Orange prominent Padmaraga is preferred by German and European buyers.

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Orangish pink Padmaraga50 50 % Padmaraga Pinkish Orange PadmaragaColouring elements in CorundumRuby- Cr3+Blue - Fe2+/ Ti4+Yellow- Fe3+, Colour centersOrange- Cr3+, Fe3+, Colour centersPadmaraga- Cr3+, Fe3+, Colour centersGreen - Fe2+Purple- Cr3+, Fe2+, Ti4+Pink- Cr3+

24Colour Centers25Electron imbalance of crystal lattice, creates colour centers.It may be naturally occurring or could be created by supplying energy. Colour Comparison 26

30% - 70%70% - 30% 50% - 50%PinkOrange (Orangish Pink)(Ideal colour of Padmaraga)(Pinkish Orange)References Hughes. W. Richard, Ruby and Sapphire, USA, 1997, 01st edition, 51, 57, 83, 109, 200, 398 ppDharmaratne. P.G.R., Gemmology, Sri Lanka, 2007, 01st edition, 39 p.Hughes. W. Richard, Walking the line in ruby and Sapphire, www. Palagems.comHughes. W. Richard, www. Palagems.com Padparadscha Sapphire buying Guide.Webster Robert, Gemmologists Compendium, 1970, 01st edition, 161 p.Read Peter G, Gemmology, 2006, Third edition, 70 p,Read Peter G, Dictionary of Gemmology, 1982, 01st edition, 45 p. 27Thank you!28