Tuesday, August 19, 2014

platinum ring color
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. It Is in Group 10 if the periodic table of elements. A dense, malleable, ductile, precious, gray-white transition metal. It is resistant to corrosion and occurs in some nickel and copper ores along with some native deposits. It is used in jewelry, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry and catalytic converter.

CHARACTERISTICS OF PLATINUM
  • Is silvery-white in appearance, lustrous, ductile and malleable
  • It does not oxidize at any temperature
  • Does not tarnish and resist corrosion
  • Insoluble n hydrochloric and nitric acid but dissolves in equal regia to form chloroplatinic acid.
  • It is more precious than gold and silver
  • It is harder than gold and silver, so it outwears them and it not as easily scratched. Its hardness is 4 to 4.5 on MOH’s scale of hardness about the same as iron. When Platinum is mixed with iridium or ruthenium, it becomes much harder and therefore more suitable for jewelry weat.
  • It is heavy and dense compared with other metals. It is approximately twice as heavy as silver.
PLATINUM QUALITY MARKINGS
The Platinum standard is different from other metals.  Gold purity is familiar subject: 24 karat gold equal 99.99% pure gold, 18 karat is 75% pure and 14 karat is 58% pure. In the platinum world, 1,000 parts of platinum equal 100%. All other alloys are derived from these 1,000 parts.
platinum quality markings

Percentage
Common Quality Marks
Alloy Composition
99% Platinum
Platinum
Plat
Pt
Pt1000
Pt999
999 parts per thousand platinum and 1 part other metal
95% Platinum
Platinum
Plat
950Pt
950Plat
Pt950
950 parts per thousand platinum and 50 parts other metals (usually ruthenium, iridium, cobalt, copper, tungsten, palladium or a combination of cobalt and copper
90% Platinum
900Pt
900Plat
Pt900

IRIDPLAT
10% IridPlatinum
900 parts per thousand platinum and 100 parts other metals (usually iridium or palladium)

IRIDPLAT is 900 parts per thousand platinum and 100 parts per thousand iridium
85% Platinum
850Pt
850Plat
Pt850
850 parts per thousand platinum and 150 parts other metals (usually palladium)
80% Platinum
850PT
850Plat
Pt850
800 parts per thousand platinum and  200 parts other metals.
75% Platinum
750Pt
750Plat
Pt750
750 parts per thousand platinum and 250 parts other metals.
58.5% Platinum
585Plat
415Pall
585 parts per thousand platinum and 415 thousand platinum.


How to Appraise Platinum
  1. Platinum should have quality markings as to its fitness Pt1000; Pt900; Pt850; Pt800; Pt750; Pt700; Pt500
  2. Do not accept articles without quality markings even if it is Platinum (no basis for valuation when pawned.)
  3. Platinum usually have uneven surfaces, not shiny and lustrous.
  4. Shows deformation due to its malleability.
  5. No reaction when applied with Nitric acid
  6. Heavy and usually have diamonds.

Other Factors to Consider in Appraising Platinum

METAL
COLOR
LUSTER
WEIGHT
CHARACTERISTICS/USAGE
Platinum
Grayish
Dull
Heavy and dense
Malleable and ductile
With markings as to fineness
No reaction on Nitric Acid
Harder than silver
Titanium
Gray
Shiny
Lightweight
100% hypoallergenic
Hard metal
Cannot be revised
Used as aircraft metals for low weight
Cannot be resized
Does not tarnish and corrode
Silver
White
Lighter than platinum

Malleable
Corrosion-resistant
Does not react to chemical but react to sulfur (present in the air)
Tarnish due to sulfur
Usually stamped as silver
No reaction on Nitric Acid
Stainless Steel
White
Shiny
Lighter than platinum
Usually stamp as stainless steel
No reaction to Nitric Acid
Does not stain due to chromium-rich in oxide film