Charts & Conversions

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Charts & Conversions

Weights

Relative Weights

Formula to calculate metal weight and cost from wax models:

  • Wax weight (dwt.*) x specific gravity of desired metal** = weight of casting in dwt. x Cost/dwt. + Labor Charges = Cost of Casting.
  • Allow some additional weight for the remaining gate.

The top line is the known material (in pennyweights). The first column is the desired material. For example, if you have a wax that weighs .7 dwt, and you want to know its corresponding weight in platinum, go down the wax column to platinum and multiply .7 dwt. (wax weight) by 21.45. 15.02 dwt’s is the corresponding weight in platinum.

Wax Sterling 10Y 14Y 18Y 14W 18W Platinum
Sterling 10.36 1.00 0.90 0.79 0.67 0.82 0.71 0.49
10Y 11.60 1.11 1.00 0.89 0.74 0.92 0.79 0.54
14Y 13.08 1.27 1.13 1.00 0.84 1.03 0.89 0.61
18Y 15.60 1.49 1.34 1.19 1.00 1.23 1.06 0.73
14W 12.65 1.22 1.09 0.97 0.81 1.00 0.86 0.59
18W 14.65 1.41 1.26 1.12 0.94 1.16 1.00 0.68
PT 21.45 2.04 1.85 1.64 1.38 1.70 1.46 1.00

*The specific gravity of wax is 1. **See Specific Gravity Chart or Relative Weights.

Weight Conversion
To convert:
Pennyweights to grams Multiply by 1.55518
Grams to pennyweights Multiply by 0.64301
Ounces troy to grams Multiply by 31.1035
Grams to ounces troy Multiply by 0.0321507
Ounces avoirdupois to grams Multiply by 28.3495
Grams to ounces avoirdupois Multiply by 0.0352740
Ounces troy to ounces avoirdupois Multiply by 1.09714
Ounces avoirdupois to ounces troy Multiply by 0.911458
Pounds avoirdupois to kilograms Multiply by 0.4535924
Kilograms to pounds avoirdupois Multiply by 2.20462
Kilograms to ounces avoirdupois Multiply by 35.2740
Kilograms to ounces troy Multiply by 32.1507

 

Carat Weight
Used in Weighing Precious and Semi-Precious Stones
1 carat = 0.20 grams
1 gram = 5 carats
1 carat = 3.086 grains troy
1 carat = 0.007 ounce avoirdupois
1 carat = 100 points

 

Troy Weight
Used in Weighing the Precious Metals
24 grains 1 pennyweight
20 pennyweights (dwt.) 1 ounce troy
12 ounces 1 pound troy
5760 grains 1 pound troy
The troy ounce is about 10% heavier than the avoirdupois ounce.
31.1035 grams 1 ounce troy
1 gram 15.432 grains troy
1.555 grams 1 pennyweight (dwt.)

Temperatures

Torch Fuel Characteristics and Temperatures
Chemical Fuel Formula Special Characteristics Flame Temp. w/Oxygen Flame Temp. w/Air BTU per lb.
Acetylene C2H2 Burns hottest; popular fuel gas; not recommended for use with platinum 6300°F 4217°F 21,499
Natural Gas ** Burns clean; economical to use 4600°F 3420°F —
Propane C3H8 Burns clean; economical to use 4780°F 3497°F 21,260
Butane C4H10 Low heat; available in portable containers 4995°F 3443°F 21,298
Hydrogen H2 High heat; cleaner than acetylene 4850°F 3713°F 61,085
MAPP® C3H4 Somewhat concentrated high-temperature flame 5300°F 3600°F 2300

** Typical analysis: methane 83.4%, ethane 15.8%, nitrogen 0.8%.

High Temperature Judged By Color
°F °C Color
752 400 Red heat, visible in dark
885 474 Red heat, visible in twilight
975 525 Red heat, visible in daylight
1077 581 Red heat, visible in sunlight
1292 700 Dark red
1472 800 Dull cherry red
1652 900 Cherry red
1832 1000 Bright cherry red
2012 1100 Orange-red
2192 1200 Orange-yellow
2372 1300 Yellow-white
2552 1400 White welding heat
2732 1500 Brilliant white
2912 1600 Dazzling white, blue-white

 

Annealing Temperature Guide

Time at the full annealing temperature will depend on the thickness of the section, but 1 minute per mm of section should be sufficient for thickness up to about 5 mm. Too frequent annealing or annealing for too long can cause grain growth which may make subsequent working or polishing to a smooth surface more difficult.

Specific Gravity and Metal Melting Points
Metal Melting Point °C Melting Point °F Specific Metal Melting Point °C Melting Point °F Specific
Aluminum 660 1220 2.7 Iridium 2454 4450 22.5
Bronze 1060 1945 8.8 Iron 1535 2793 7.9
Copper 1083 1981 8.9 Lead 327 621 11.3
Gold (fine) 1063 1945 19.3 Nickel 1455 2651 8.8
22K Yellow 977 1790 17.3 Nickel Silver 1110 2030 8.8
22K Coin 940 1724 17.2 Palladium 1549 2820 12.2
18K Yellow 1030 1885 15.5 Platinum (Pure) 1774 3225 21.4
18K Green 966 1770 15.6 5% Cobalt 1765 3209 20.8
18K Rose 932 1710 15.5 5% Iridium 1790 3254 21.4
18K White 940 1725 15.7 10% Iridium 1800 3272 21.5
14K Yellow 960 1760 13.4 5% Ruthenium 1795 3263 20.7
14K Green 835 1535 13.6 Silver (Fine) 961 1762 10.6
14K Rose 827 1520 13.4 Sterling 920 1640 10.4
14K White 975 1785 13.7 Stainless Steel 1371 2500 7.8
10K Yellow 980 1796 11.6 Titanium 1800 3272 4.5

Measurements

Fluid Measurement

  • 1 quart = 32 ounces (fluid) = 2 pints = 1/4 gallon = 57 cubic inches
  • 1 gallon = 4 quarts = 128 ounces (fluid) = 3.78 litre and 231 cubic inches = 0.134 cubic feet
  • 1 litre = 1,000 cc (slightly more than 1 quart U.S.) = 0.264 U.S. gallons
  • 1 cubic foot = 7.481 U.S. gallons = 1,728 cubic inches
  • 1 imperial gallon = 1.2 U.S. gallons = 4.59 litre = 277.27 cubic inches

Length Conversion

To convert:
Millimetres to inches Multiply by 0.0393701
Inches to millimetres Multiply by 25.4
Metres to inches Multiply by 39.3701
Inches to metres Multiply by 0.0254
  • 1 inch = 25.4 millimetres
  • 1 millimetre = 0.0393 inch
  • 1 metre = 1,000,000 microns
  • 1 micron = 0.000039 inch

Area and Volume Conversion

 

To convert:
Square inches to square millimetres Multiply by 645.16
Square inches to square decimetres Multiply by 0.064516
Square decimetres to square inches Multiply by 15.50
Square millimetres to square inches Multiply by 0.00155
Cubic inches to cubic centimetres Multiply by 16.3871
Cubic centimetres to cubic inches Multiply by 0.061024

Rules Relating to Circles

  • The circumference of a circle is the diameter x 3.1416.
  • The diameter of a circle is the circumference multiplied by .31831.
  • The area of a circle is the diameter x itself x .7854.
  • A circle is .7854 times as heavy as a square of the same size. The loss in cutting a circle from a square is .2146 of the weight of the square.

Stone Conversions

Carat Size Round Shape MM Carat Size Round Shape MM Carat Size Round Shape MM
.005 1.0 .11 3.1 .40 4.8
.01 1.3 .12 3.2 .50 5.2
.015 1.5 .14 3.3 .60 5.4
.02 1.7 .15 3.4 .65 5.6
.025 1.8 .16 3.5 .75 5.8
.03 2.0 .17 3.6 .80 6.0
.035 2.1 .18 3.7 1.00 6.5
.04 2.2 .20 3.8 1.25 7.0
.05 2.4 .22 3.9 1.33 7.2
.06 2.5 .23 4.0 1.50 7.4
.07 2.7 .25 4.1 1.75 7.8
.08 2.8 .30 4.2 2.00 8.2
.09 2.9 .33 4.4 2.50 8.8
.10 3.0 .38 4.6 3.00 9.4

 

Fineness of Gold (Karats)

9K .3750 17K .7083
10K .4167 18K .7500
11K .4583 19K .7917
12K .5000 20K .8333
13K .5417 21K .8750
14K .5833 22K .9167
15K .6250 23K .9583
16K .6667 24K 1.000

 

Wire and Drill Sizes

B&S mm Inches Thou. Inches Fractions Drill Size B&S mm Inches
Thou.		 Inches Fractions Drill Size
0 8.5 .325 21/64 16 1.29 .050 54
1 7.35 .289 9/32 17 1.15 .045 3/64 55
2 6.54 .258 1/4 18 1.02 .040 56
3 5.83 .229 7/32 1 19 .912 .036 60
4 5.19 .204 13/64 6 20 .813 .032 1/32 65
5 4.62 .182 3/16 15 21 .724 .029 67
6 4.11 .162 5/32 20 22 .643 .025 70
7 3.67 .144 9/64 27 23 .574 .023 71
8 3.26 .129 1/8 30 24 .511 .020 74
10 2.59 .102 38 25 .455 .018 75
11 2.30 .090 3/32 43 26 .404 .016 1/64 77
12 2.05 .080 5/64 46 27 .361 .014 78
13 1.83 .072 50 28 .330 .013 79
14 1.63 .064 1/16 51 29 .279 .011 80
15 1.45 .057 52 30 .254 .010

 

Ring Size

Size Inside Diameter
Inch		 Inside Diameter
mm 		Size Inside Diameter
Inch		 Inside Diameter
mm
1 .486 12.344 7 1/2 .694 17.628
1 1/2 .502 12.751 8 .710 18.034
2 .518 13.157 8 1/2 .7265 18.453
2 1/2 .534 13.564 9 .743 18.872
3 .550 13.970 9 1/2 .759 19.279
3 1/2 .566 14.376 10 .778 19.761
4 .582 14.783 10 1/2 .794 20.168
4 1/2 .598 15.189 11 .811 20.599
5 .6141 15.597 11 1/2 .8271 21.008
5 1/2 .6300 16.002 12 .843 21.412
6 .6455 16.396 12 1/2 .859 21.819
6 1/2 .662 16.815 13 .875 22.225
7 .678 17.221

Standard Reference Chart for Ring Size Conversions

US Size Dia. -inch Dia. in MM Metric -MM British French German Japanese Swiss
0000 .390 9.91   -        
00 .422 10.72   -        
0 .454 11.53   -        
1/2 .474 11.95   A        
3/4 .482 12.18   A 1/2        
1 .487 12.37 38.9 B     1  
1 1/4 - 12.60 39.6 B 1/2        
1 1/2 .503 12.78 40.2 C        
1 3/4 - 13.00 40.8 C 1/2        
2 .520 13.21 41.5 D 41 1/2 13 1/2 2 1 1/2
2 1/4 - 13.41 42.1 D 1/2 - -    
2 1/2 .536 13.61 42.7 E 42 3/4 13 3/4 3 2 3/4
2 3/4 - 13.83 43.4 E 1/2 - -    
3 .553 14.05 44.0 F 44 14 4 4
3 1/8 - 14.15 44.3 F 1/2 - -    
3 1/4 - 14.25 44.6 - - -    
3 3/8 - 14.36 44.9 G 45 1/4 - 5 5 1/4
3 1/2 .569 14.45 45.2 - - 14 1/2    
US Size Dia. -inch Dia. in MM Metric -MM British French German Japanese Swiss
3 5/8 - 14.56 45.6 G 1/2 -   6  
3 3/4 - 14.65 45.9 H 46 1/2     6 1/2
4 .585 14.86 46.5 H 1/2 - 15 7  
4 1/4 - 15.04 47.1 I 47 3/4     7 3/4
4 1/2 .601 15.27 47.8 I 1/2 - 15 1/4 8  
4 5/8 - 15.40 48.1 J 49 15 1/2   9
4 3/4 - 15.53 48.4 - -      
5 .618 15.70 49.0 J 1/2 - 15 3/4 9  
5 1/8 - 15.80 49.3 K 50     10
5 1/4 - 15.90 49.6 - -      
5 3/8 - 16.0 50.0 K 1/2 -   10  
5 1/2 .634 16.10 50.3 L 51 3/4 16   11 3/4
5 3/4 - 16.30 50.9 - -      
5 7/8 - 16.41 51.3 L 1/2 -      
6 .650 16.51 51.5 M 52 3/4 16 1/2 12 12 3/4
6 1/4 - 16.71 52.2 M 1/2 -      
6 1/2 .666 16.92 52.8 N 54 17 13 14
6 3/4 - 17.13 53.4 N 1/2 -      
US Size Dia. -inch Dia. in MM Metric -MM British French German Japanese Swiss
7 .683 17.35 54.0 O 55 1/4 17 1/4 14 15 1/4
7 1/4 - 17.45 54.7 O 1/2 -      
7 1/2 .699 17.75 55.3 P 56 1/2 17 3/4 15 16 1/2
7 3/4 - 17.97 55.9 P 1/2 -      
8 .716 18.19 56.6 Q 57 3/4 18 16 17 3/4
8 1/4 - 18.35 57.2 Q 1/2 -      
8 1/2 .732 18.53 57.8 - - 18 1/2 17  
8 5/8 - 18.61 58.4 R 59     19
8 3/4 - 18.69 58.4 - -      
8 7/8 - 18.80 59.0 R 1/2 -      
9 .748 18.89 59.1 - - 19 18  
9 1/8 - 19.10 59.4 S 60 1/4     20 1/4
9 1/4 - 19.22 59.7 - -      
9 3/8 - 19.31 60.0 S 1/2 -      
9 1/2 .764 19.41 60.3 - - 19 1/2 19  
9 5/8 - 19.51 60.6 T 61 1/2     21 1/2
9 3/4 - 19.62 60.9 - -      
10 .781 19.84 61.6 T 1/2 - 20 20  
US Size Dia. -inch Dia. in MM Metric -MM British French German Japanese Swiss
10 1/4 - 20.02 62.2 U 62 3/4   21 22 3/4
10 1/2 .797 20.20

 62.8 U 1/2 - 20 1/4 22  
10 5/8 - 20.32 63.1 V 63     23 3/4
10 3/4 - 20.44 63.5 - -      
11 .814 20.68 64.1 V 1/2 - 20 3/4 23  
11 1/8 - 20.76 64.3 W 65     25
11 1/4 - 20.85 64.7 - -      
11 3/8 - 20.94 65.0 W 1/2 -      
11 1/2 - 21.08 65.3 - - 21 24  
11 5/8 .830 21.18 65.7 X 66 1/4     26 1/4
11 3/4 - 21.24 66.0 - -      
11 7/8 - 21.30 66.3 X 1/2 -      
12 .846 21.49 66.6 Y 67 1/2 21 1/4 25 27 1/2
12 1/4 - 21.69 67.2 Y 1/2 -      
12 1/2 .862 21.89 67.9 Z 68 3/4 21 3/4 26 28 3/4
12 3/4 - 22.10 68.5 Z 1/2 -      
13 .879 22.33 69.1 - - 22 27  
US Size Dia. -inch Dia. in MM Metric -MM British French German Japanese Swiss
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