Gold is a highly sought-after precious metal that for many centuries has been used as money, a store of value and in jewelry. The metal occurs as nuggets or grains in rocks and in alluvial deposits and is one of the coinage metals. It is a soft, shiny, yellow, dense, malleable, and ductile (trivalent and univalent) transition metal. Modern industrial uses include dentistry and electronics. Gold forms the basis for a monetary standard used by the International Monetary Fund (IMF) and the Bank for International Settlements (BIS). Its ISO currency code is XAU.
Gold is a chemical element in the periodic table with the symbol Au (from the Latin aurum) and atomic number 79. The adjective auric refers to something made of gold. Gold does not react with most chemicals but is attacked by chlorine, fluorine, aqua regia and cyanide. Gold dissolves in mercury. In particular, gold is insoluble in nitric acid, which will dissolve most other metals. Nitric acid has long been used to confirm the presence of gold in items.
Silver is a very ductile and malleable (slightly harder than gold) univalent coinage metal with a brilliant white metallic luster that can take a high degree of polish. It has the highest electrical conductivity of all metals, even higher than copper, but its greater cost and tarnishability has prevented it from being widely used in place of copper for electrical purposes.
Pure silver also has the highest thermal conductivity, whitest color, the highest optical reflectivity (although it is a poor reflector of ultraviolet light), and the lowest contact resistance of any metal. Silver halides are photosensitive and are remarkable for the effect of light upon them. This metal is stable in pure air and water, but does tarnish when it is exposed to ozone, hydrogen sulfide, or air containing sulfur. The most common oxidation state of silver is +1 (for example, silver nitrate; AgNO3); a few +2 (for example, silver(II) fluoride; AgF2) and +3 compounds (for example, silver(III) persulfate; Ag2(SO5)3) are also known.
titanium is a chemical element in the periodic table that has the symbol Ti and atomic number 22. It is a light, strong, lustrous, corrosion-resistant (including resistance to sea water and chlorine) transition metal with a white-silvery-metallic color. Titanium is used in strong lightweight alloys (most notably with iron and aluminium), and in powdered form to other materials, such as graphite composites. Its most common compound, titanium dioxide, is used in white pigments.
The element occurs within numerous minerals with the main sources being rutile and ilmenite, which are widely distributed over the Earth. There are two allotropic forms and five naturally occurring isotopes of this element; 46Ti through 50Ti with 48Ti being the most abundant (73.8%). One of titanium's most notable characteristics is that it is as strong as steel but is only 60% its density. Titanium's properties are chemically and physically similar to zirconium.
Platinum:
When pure the metal appears greyish-white and firm. The metal is corrosion-resistant. The catalytic properties of the six platinum family metals are outstanding. For this catalytic property, platinum is used in catalytic converters, incorporated in automobile exhaust systems, as well as tips of spark plugs.
Platinum's wear- and tarnish-resistance characteristics are well suited for making fine jewelry. Platinum is more precious than gold. The price of platinum changes along with its availability, but it normally costs slightly less than twice the price of gold[1]. In the 18th century, platinum's rarity made King Louis XV of France declare it the only metal fit for a king.