8th to 11th century - Sri Lanka
Late Anuradhapura Period - Kahavanu

OMRS Catalog Identification Numbers Codrington's 1924
Ceylon Coins & Currency
Kahavanu - 1 Fractions
Bottom Stalk Ends Compartments in Treasury Ada
1/2 Pala
1/4 Aka
1/8 Kaha
vanu Ada
1/2 Pala
1/4 Aka
1/8
Type SubType (Objects in Hand) Left Right Balls 6 8 10 12 14+
I Chank on ghata (Vase) Chank Chank 4T S12 S13 S25 I I
I Chank Chank Chank 4T S20 S33 I I
I Ira-sanda (Sun-Moon) Chank Flower 4T S01 S02 S04 S07 S23 I A(1) I
I Ira-sanda (Sun-Moon) Naval Chank Flower 4T S09 S11 S08 I A(2)
I Adahanda (Crescent Moon) Chank Flower 4T S22 S21 I
I Purnaghata (Full Vase) Flower Flower 4T LC S14 C48 S27 S28 I B I I
I Srivatsa Crescent Flower 4T S18 S19 S32 I I
I Byoankura (Bo plant) Crescent Flower 4T S16 S30 S31 I I I
I Target+Lotus-Bud+Crescent Crescent Crescent 4T S17 I

II Adahanda+Lamp & Lotus Chank Chank 4T S49 - II -
II Adahanda & Lotus Chank Chank 4T S38 S39 S41 - S61 S62 II(2) - II(2) II(2)
II Adahanda & Lotus Chank Chank 3T LC S42 - - - II - - -
II Adahanda & Lotus Flower Flower 3T B30 S45 S46 - - - II - - -
II Lotus & Adahanda Chank Flower 4T S34 S36 - S59 S60 II(1) - II(1) II(1)
II Lotus & Adahanda Adahanda Chank 3T S37 - - - II - - -
II Double Lotus Adahanda Adahanda 3T B30 S54 - S65 S66 II - II(3) II
II Adahanda & Lotus Adahanda Adahanda 3T B30 S44 - - - II(2)v - - -
II Adahanda & Lotus Chank Adahanda 3T S47 B30 S48 - - - II - - -
II Trisula+Adahanda & Lotus Chank Chank 3T B30 S57 S58 - II -
II Trisula & Adahanda Lotus Chank 3T S56 - S67 S68 II - II II
II Double Adahanda Lotus Chank 3T S50 S52 S53 - C65 II(3) - II(4) II(3)
II Jasmin-Bud & Lotus Lotus Lotus 3T S55 - II(4) -
II Adahanda & Lotus+Crescent - S63 S64 II - II II

III Ball & Annulet Chank JasFlower 1A+4T LC S69 - S73 S74 III A - IIIA III(1)
III Jasmine-Flower & Chank Chank JasFlower 1A+4T S72 S71 S70 - S75 S78 III B - IIIB III(2)

This table has been made into an excel file and saved as HTML including metallurgy measured using X-ray Florescence(XRF)
Sheet KT: The Gold fraction in Karats and
Sheet Ag%Cu The Percentage of Silver in the Silver-Copper alloy with which Gold has been mixed.
Please Note that the above purity of Gold in Karats, are based on a single coin of each subtype and variety we have measured with XRF so far. A significant sample needs to be measured of each variety and averaged, before any statistical analysis. All metal composition was measured using X-ray Fluorescence (XRF) method in Mangala Jewellery of Kandy with specific gravity measure as a control against plated coins.
From these measurements we can make some preliminary observations on the Kahavanu Types, subtypes and varieties.

The Kahavanu has Gold purity between 18 Karat (75% Au) and 8 Karat (33% Au) with Type I higher in purity than Type II which is higher than Type III in general.

The Gold purity appears to depend on subtypes we have identified including the symbols on either side of the Stalk under the feet of the standing Kuvera and the number of targets 4 or 3.

The number of compartments in the "treasury" below the seated Bahirava, which has traditionally been considered a measure of gold purity, show smaller differences than subtype and is at most a secondary measure.

Type II Kahavanu with 4 Targets or Annulets seen on all Type I and few Type II on obverse have more Gold Purity than those with 3 Targets in general.

All these ancient coins have been alloyed with lot more Silver than Copper.

The ancient Kahavanu alloyed with more Silver than Copper enables the identification of most modern fakes made using Gold from British Gold Sovereigns, which has no Silver.

Variations
OMRS-1 has 4 Annulets rather than 4 targets

Notes
14+ is 14 or more compartments i.e. 14, 16, 18. or 24
LC in Lakdiva Collection (3)
B30 Boekel Hoard of 30 TypeII coins (5)
C## Shown in Codrinton's CCC plate. (2)

I am studying Medieval Lankan Gold coins from the 8th to 11th century. From the metallurgy of the coin measured with XRF there appears to be some clear dependence on subtype and this could fall into a sequence that may be chronological.
Can't be infered from Single coins, but try to get measurements of as many coins as possible with collectors and Museums.
I want to have a database with a web form into which collectors can submit information, and then look at means and dispersions of metallurgy.

Statistics

Each Lankan medieval Gold Kahavanu is classified into 3 Primary Types and described with 2 Symbols (Objects in Hand) which gives 9, 9, and 2 primary subtypes for Types I, II, and III.
Based on the same two symbols each of the primary subtypes has factions Pala(1/4) and Aka(1/8), and the Type I has an additional fraction Ada(1/2) known for 2 of the 9 subtypes.
The Full Kahavanu of two of the primary Type II subtypes Adahanda & Lotus and Lotus & Adahanda can be divided into 5 and 2 more subtypes based on symbols at the left and right ends of the Stalk below the Standing Kuvera and the number of targets 4 or 3 on obverse.
So a total 9+14+2=25 subtypes for Full Kahavanu of which 9+13+2=24 are known.
Each of these can have up to 5 varieties based on the number of compartments in the Asana (Treasury) below the seated Bahirava.
Giving a total of 19+27+5=51 known varieties of Kahavanu with images.
For fractions with 9+9+2=20 possibilities.
The Ada(1/2) has 2 known of 9 Type I possibilities.
The Pala(1/4) has 4+5+2=11 known of 20 Type I, II, and III possibilities.
The Aka(1/8) has 2+6+2=10 known of 20 Type I, II, and III possibilities.

Ignoring these detail we have a total of 7 symbols describing each variety of coin so far.

Each coin has in addition
2 images Obverse and Reverse
Weight : 0.01 grams precision
Weight in Water : 0.01 grams precision
Gold : Au%
Silver : Ag%
Copper : Cu%

Derived

Volume Estimate  0.01 cc (Weight in Air - Weight in Water)
Specific Gravity          Weight in Air/(Weight in Air - Weight in Water)
Gold                      Karat  Au%*24
Silver Fraction in Alloy with Copper   Ag% / (Ag%+Cu%)

OMRS Catalog
Type   I  9 SubTypes. 17 varieties of 22 Kahavanu; 2 Ada; 4 of  6 Pala; and 2 of  3 Aka
Type  II 14 SubTypes. 21 varieties of 25 Kahavanu; 0 Ada; 5 of  5 Pala; and 5 of  5 Aka
Type III  2 SubTypes.  4 varieties of  4 Kahavanu; 0 Ada; 2 of  2 Pala; and 2 of  4 Aka
Total    25           42 varieties of 51 Kahavanu; 2 Ada;11 of 13 Pala; and 9 of 12 Aka
With Additions from other collections
Type   I  9 SubTypes. 19 varieties Kahavanu; 2 Ada;  4 Pala; and  2 Aka
Type  II 14 SubTypes. 27 varieties Kahavanu; 0 Ada;  5 Pala; and  6 Aka
Type III  2 SubTypes.  5 varieties Kahavanu; 0 Ada;  2 Pala; and  2 Aka
Total    25           51 varieties Kahavanu; 2 Ada; 11 Pala; and 10 Aka

Text from * Ceylon Coins and Currency By H. W. Codrington. Colombo 1924
Page 54 Chapter V Medieval Ceylon - Kahavanu
* Medieval Gold Coins of Sri Lanka ( 700 - 1100 )
by O. M. R. Sirisena 2002 Colombo, Sri Lanka

8th to 11th century - Sri Lanka Late Anuradhapura Period - Kahavanu

Statistics

8th to 11th century - Sri Lanka
Late Anuradhapura Period - Kahavanu