Emeralds

Emeralds, like all colored gemstones, are graded using four basic parameters – the four Cs of Gemstones: Color, Cut, Clarity and Crystal. The last C, crystal is a synonym that begins with C for transparency or what gemologists call diaphaneity. Before the 20th century, jewelers used the term water as in a gem of the finest water to express the combination of two qualities, color and crystal. Normally, in the grading of colored gemstones, color is by far the most important criterion. However, in the grading of emerald, crystal considered a close second. Both are necessary conditions. A fine emerald must possess not only a pure verdant green hue as described below, but also a high degree of transparency considered a top gem. In the 1960s, the American jewelry industry changed the definition of emerald to include the green vanadium-bearing beryl as emerald. As a result, vanadium emeralds purchased as emeralds in the United States recognized as such in the UK and Europe. In America, the distinction between traditional emeralds and the new vanadium kind reflected in the use of terms such as Colombian Emerald. Scientifically speaking, color divided into three components: hue, saturation and tone. Yellow and blue, the hues found adjacent to green on the spectral color wheel, are the normal secondary hues found in emerald. Emeralds occur in hues ranging from yellow-green to blue-green. The primary hue must be green. Only gems that are medium to dark in tone considered emerald. Light-toned gems known by the species name, green beryl. In addition, the hue must be bright (vivid). Gray is the normal saturation modifier or mask found in emerald. A grayish green hue is a dull green. Emerald tends to have numerous inclusions and surface breaking fissures. Emerald graded by eye. Thus, if an emerald has no visible inclusions to the eye it considered flawless. Stones that lack surface breaking fissures are extremely rare and therefore almost all emeralds are treated, oiled, to enhance the apparent clarity. Eye-clean stones of a vivid primary green hue with no more than 15% of any secondary hue or combination of a medium-dark tone command the highest prices.6 This relative crystal non-uniformity makes emeralds more likely than other gemstones to be cut into cabochons, rather than faceted shapes.

Online bingo is the game of bingo played on the Internet.

Unlike balls used in regular bingo halls, online bingo sites use a random number generator. Most bingo halls also offer links to online poker and casino offerings as the patrons are often in the target market. One notable feature of online bingo is the chat functionality. Bingo sites strive to foster a sense of community and interaction between players as this helps customer retention.

Playing bingo online, players can make use of optional features, which make playing the game easier, such as auto-daub. Auto-daub automatically marks off the numbers on cards as they are called, so players don't have to. Most software providers support other gaming features as Best Card Sorting and Best Card Highlighting where players cards are sorted and highlighted by closest to bingo. Some of these features are designed to free players to enjoy the communal pleasantries of the chat features.

There is variety among the different kinds of bingo games that can be played. For example, some inexpensive game rooms appeal to the player who may want to play for just a 10 cents or 10 pence; some bingo games only allow players to purchase the same amount of cards so they are not competing against the high rollers out there who buy many cards for the same game.

The first slot machine was invented by Charles Fey of San Francisco, California, U.S., who devised a much simpler automatic mechanism. Most assert that Fey invented the machine in 1887; however some believe that he may have conceived the machine in 1895. Due to the vast number of possible wins with the original poker card based game, it proved practically impossible to come up with a way to make a machine capable of making an automatic payout for all possible winning combinations. Charles Fey devised a machine with three spinning reels containing a total of five symbols – horseshoes, diamonds, spades, hearts, and a Liberty Bell, which also gave the machine its name. By replacing ten cards with five symbols and using three reels instead of five drums, the complexity of reading a win was considerably reduced, allowing Fey to devise an effective automatic payout mechanism. Three bells in a row produced the biggest payoff, ten nickels. Liberty Bell was a huge success and spawned a thriving mechanical gaming device industry. Even when the use of these gambling devices was banned in his home state after a few years, Fey still couldn't keep up with demand for the game elsewhere. Liberty Bell machine was so popular that it was copied by many slot machine manufacturers. Thus in 1907, manufacturer Herbert Mills from Chicago produced a slot machine called the Operator Bell. By 1908 lots of bell machines were installed in most cigar stores, saloons, bowling alleys, brothels and barber stores. The original Liberty Bell slot machine can still be seen at the Liberty Belle Saloon & Restaurant in Reno, Nevada. Sittman and Pitt of Brooklyn, New York, U.S. developed a gambling machine in 1891 which was a precursor to the modern slot machine. It contained five drums holding a total of 50 card faces and was based on poker. This machine proved extremely popular and soon many bars in the city had one or more of the machines. Players would insert a nickel and pull a lever, which would spin the drums and the cards they held, the player hoping for a good poker hand. There was no direct payout mechanism, so a pair of kings might get the player a free beer, whereas a royal flush could pay out cigars or drinks, the prizes wholly dependent on what was on offer at the local establishment. To make the odds better for the house, two cards were typically removed from the deck: the ten of spades and the jack of hearts, which doubles the odds against winning a royal flush. The drums could also be rearranged to further reduce a player's chance of winning. Another early machine gave out winnings in the form of fruit flavored chewing gums with pictures of the flavours as symbols on the reels. The popular cherry and melon symbols derive from this machine. The BAR symbol now common in slot machines was derived from an early logo of the Bell-Fruit Gum Company. The payment of food prizes was a commonly used technique to avoid laws against gambling in a number of states, and for this reason a number of gumball and other vending machines were regarded with mistrust by the courts. The two Iowa cases of State v. Ellis6 and State v. Striggles7 are both used in classes on criminal law to illustrate the concept of reliance upon authority as it relates to the axiomatic ignorantia juris non excusat Ignorance of the law is no excuse.8 In these cases, a mint vending machine was declared to be a gambling device because by internally manufactured chance the machine would occasionally give the next user a number of tokens exchangeable for more candy. Despite the fact that the result of the next use would be displayed on the machine, both courts ruled that The inducement for each play was the chance that by that play the machine would be set to indicate that it would pay checks on the following play. The thing that attracted the player was the chance that ultimately he would receive something for nothing. The machine appealed to the player's propensity to gamble, and that is a vice.9 In 1963, Bally developed the first fully electromechanical slot machine called Money Honey, although earlier machines such as the High Hand draw poker machine by Bally had exhibited the basics of electromechanical construction as early as 1940. The electromechanical approach of the 1960s allowed Money Honey to be the first slot machine with a bottomless hopper and automatic payout, of up to 500 coins, without the help of an attendant. The popularity of this machine led to the increasing predominance of electronic games, and the side lever soon became vestigial. The first true, video slot machine was developed in 1976 in an industrial suite in Kearney Mesa, CA by N. Cerracchio, R. Greene, W. Beckman, J. Reukes, and L. Black under the direction of Fortune Coin Co., Las Vegas, NV. This slot machine used a modified 19 Sony Trinitron color receiver for the display, and logic boards for all slot machine functions. The prototype was mounted in a full size, show-ready slot machine cabinet. The first production units went on trial in the Las Vegas Hilton Hotel. After some cheat-proofing modifications, the video slot machine was approved by the Nevada State Gaming Commission and eventually found popularity in Las Vegas Strip and downtown casinos. Fortune Coin Co. and their video slot machine technology were purchased by IGT International Gaming Technology in 1978. The first American video slot machine to offer a second screen bonus round was Reel 'Em In developed by WMS Industries Inc. in 1996. This type of machine had appeared in Australia from at least 1994 with the Three Bags Full game. In this type of machine, the display changes to provide a different game where an additional payout may be won or accumulated.

Card Game Rules

Any specific card game imposes restrictions on the number of players. The most significant dividing lines run between one-player games and two-player games, and between two-player games and multi-player games. Card games for one player are known as solitaire or patience card games.  Generally speaking, they are in many ways special and atypical, although some of them have given rise to two- or multi-player games such as Spite and Malice.

In card games for two players, usually not all cards are distributed to the players, as they would otherwise have perfect information about the game state. Two-player games have always been immensely popular and include some of the most significant card games such as piquet, bezique, sixty-six, klaberjass, gin rummy and cribbage. Many multi-player games started as two-player games that were adapted to a greater number of players. For such adaptations a number of non-obvious choices must be made beginning with the choice of a game orientation.

One way of extending a two-player game to more players is by building two teams of equal size. A common case is four players in two fixed partnerships, sitting crosswise as in whist and contract bridge. Partners sit opposite to each other and cannot see each other's hands. If communication between the partners is allowed at all, then it is usually restricted to a specific list of permitted signs and signals. 17th century French partnership games such as triomphe were special in that partners sat next to each other and were allowed to communicate freely so long as they did not exchange cards or played out of order.

Another way of extending a two-player game to more players is as a cut-throat game, in which all players fight on their own, and win or lose alone. Most cut-throat card games are round games, i.e. they can be played by any number of players starting from two or three, so long as there are enough cards for all.

For some of the most interesting games such as ombre, tarot and skat card game, the associations between players change from hand to hand. Ultimately players all play on their own, but for each hand, some game mechanism divides the players into two teams. Most typically these are solo games, i.e. games in which one player becomes the soloist and has to achieve some objective against the others, who form a team and win or lose all their points jointly. But in games for more than three players, there may also be a mechanism that selects two players who then have to play against the others.