They're made from two separate pieces ! The outer 'ring' is heated so it expands, and the inners are inserted. When the outer ring cools, it shrinks forming a VERY tight fit.
It should be fairly easy since the standard alloy 1 pound coin is yellow-ish and the silver one is, well, silver. The silver one is also a proof so it should have very reflective mirror like surfaces.
A 1889 gold 5 pound coin is worth 5 pounds of gold, while a 1889 2 pound gold coin is only worth 2 pounds of gold.
None that I know of. The idea behind having a different metal in the core of any coin is to increase the coin's structural integrity. Gold is quite soft and though valuable, would make a poor choice for any coin. You may be thinking of a so-called bimetallic coin. Many countries issue these coins, but they're made of brass and copper-nickel, not gold and silver. Examples are the Canadian $2 coin, the European €1 and €2 coins, and the British £2 coin.
$1. Ikes were never issued in gold or gold-colored metal, only in cupronickel for circulation and silver for collector sets. Your coin was almost certainly plated for use in jewelry or something similar.
No British general circulation coin is made from gold, however, the Royal Mint produces Proof coins for serious collectors and investors. Some of these are struck in precious metals such as silver or gold, and occasionally platinum. The British One Pound coin featuring the Royal Arms on the reverse was struck in 1983, 1993, 1998, 2003 and 2008. The 2008 coin was produced as Proof FDC in silver, gold and platinum.
Old English Pounds (Sovereigns) were minted in 22 carat gold, not silver.
The US didn't make any circulating silver dollars from 1804 to 1835 inclusive. If your coin is small, gold in color, and has a picture of Andrew Jackson on it, it's a modern $1 coin and it's made of brass, not silver (that's why it's brass-colored and not silver-colored, after all!) 1829 was when Jackson was inaugurated.
The first gold Fifty Pound coin issued by the Royal Mint was in 1987.
A silver Pound coin, usually Proof FDC, is made from silver and has a silver appearance and it will also state the fineness of the silver on the box it comes in. It will also cost significantly more than One Pound to buy one. They are made for collectors and investors. The general circulation nickel-brass Pound coins have a sort of a poor gold appearance and are what you expect in your loose change. Both coin types from any one year should have the same design, front and back.
If you're referring to a large coin that's really made of silver, its value depends on the price of silver at the current time. Silver has been in the $10-$11/oz range in late 2008 but can and does change a lot. If you have a small gold-colored coin it's not silver obviously, and it's not gold either. It's an ordinary circulating brass $1 coin worth exactly one dollar.
A pound of gold weighs the same as a pound of silver, because they are both one pound. But a block of gold would weigh more than the same-sized block of silver (gold is more dense than silver, so a smaller volume weighs the same).
As I type this the value of 1 pound of gold is $18,040.00