All Ohaus scales listed here, except the LS-200, have the following features:
- Refined load cell technology
- Push button calibration
- AC/DC powered
- Tare function
- LCD display
- Auto Shutoff function
- Low battery indicator
- Calibration weight (except the LS-200, CT 600L & CT 1200)
- Gold scoop
- Removable weighing platform
- Made in USA
- 5 year warrantee
- AC adapter
- Meets legal requirements for weighing metal bought and sold. Weighs in grams, pennyweights, ounces & troy ounces. Max capacity 610 grams at .1 gram precision.$687.00
- Capacity 200 gram at .01 gram. Weighs in gram, pennyweight, ounce, troy ounce. Parts counter. Has a weigh below hook for measuring specific gravity and an easy access bracket for securing the balance. Specific gravity measurement can be used for doing very rapid and accurate assays of the jewelry you manufacture.$329.95
- Capacity 400 gram at .1 gram. Weighs in gram, pennyweight, ounce, troy ounce. Parts counter. Has a weigh below hook for measuring specific gravity and an easy access bracket for securing the balance.$229.95
- Capacity 600 gram at .1 gram. Weighs in gram, pennyweight, ounce, troy ounce. Parts counter. Has a weigh below hook for measuring specific gravity and an easy access bracket for securing the balance.$264.99
What is Specific Gravity?
Specific gravity is the weight in grams of one cubic centimeter of a metal.
The Specific Gravity Test is used to calculate the gold content of gold nuggets that contain a mixture of gold and other materials. In this example of the specific gravity test, we use gold mixed with quartz. Simply put, the formula is 3.1 x the weight in water, minus 1.9 x the weight in air:
Wet nugget weighs 74.5 grams x 3.1 = 230.95
Dry nugget weighs 96 grams x 1.9 = 182.4
230.95 - 182.4 = 48.55
31.1 = number of grams per ounce
48.55 / 31.1 = 1.56 ounces of gold
Original dry weight = 96 grams / 31.1 = 3.08 ounces.
Subtract the difference between the wet and the dry:
3.08 ounces - 1.56 ounces = 1.52 ounces.
Therefore what is left is 1.52 ounces of quartz.
"Wet" = weight in water - Put container of water (enough water to cover nugget) on scale. Tare (zero) out scale. Hang nugget by string in water. Note weight.
The specific gravity for gold is 19.3.
The specific gravity for quartz is 2.65.
The ratio between gold and quartz is 7.28 X.
Specific Gravities of Common Metals
Metal Symbol Specific Gravity Melting Point (° F) Melting Point (° C) Copper Cu 8.96 1981 1083 Gold Au 19.32 1945 1063 Iron Fe 7.87 2802 1539 Lead Pb 11.34 621 327 Nickel Ni 8.90 2651 1455 Palladium Pd 12.00 2831 1555 Platinum Pt 21.45 3224 1773 Silver Ag 10.49 1761 961
Pure gold has a density of 19.32 gm/cm3 while 14K gold has a density between 12.9 and 14.6 gm/cm3, depending upon the composition of the alloy.