There are many variations in the maker's marks used by Tiffany & Co., the below is only intended to give a basic guideline to the holloware markings.
A goodly number of the mark variations are illustrated in Charles H. Carpenter's fine book, 'Tiffany Silver'.
In the early years, a number of different silversmiths supplied Tiffany with silver holloware & flatware and marked the pieces with their own marks as well as the Tiffany marks.
The examples above only show John Moore's mark, some of the others were: William Gale, John Polhemus, Grosjean & Woodward, Wood & Hughes, Henry Hebbard, and William Bogert.
After the Moore silversmithing firm was absorbed into Tiffany & Co. (about 1870) and Tiffany began the production of its own silverware, it became the tradition to mark each piece with the initial of the Artistic Director or President of the firm. This practice continued until the mid 1960's.
 

Tiffany Holloware Pattern Numbers

Tiffany & Co's use of Pattern numbers allows us to date when a design was first put into production, as many popular designs were produced for many years, they only provide a guideline.
Using them in conjunction with the director's initial mark does often give a fairly accurate circa date.
Order numbers are, for all intents and purposes, not useful to us. They were used 'in house' to keep track of production.
Without access to the Tiffany archives, they have no real meaning.

Tiffany Holloware Pattern Numbers

1851 ~ 1 1856 ~ 301 1860 ~ 1,001 1865 ~ 1,551 1870 ~ 2,251 1875 ~ 3,801 1876 ~ 4,545 1877 ~ 4,620 1878 ~ 5,050 1879 ~ 5,370 1880 ~ 5,910 1881 ~ 6,260 1882 ~ 6,760 1883 ~ 7,300 1884 ~ 7,840 1885 ~ 8,340 1886 ~ 8,800 1887 ~ 9,260 1888 ~ 9,660 1889 ~ 10,120   1890 ~ 10,400 1891 ~ 10,820 1892 ~ 11,140 1893 ~ 11,520 1894 ~ 11,940 1895 ~ 12,220 1896 ~ 12,600 1897 ~ 13,040 1898 ~ 13,510 1899 ~ 13,900 1900 ~ 14,250 1901 ~ 14,650 1902 ~ 15,145 1903 ~ 15,550 1904 ~ 15,943 1905 ~ 16,356 1906 ~ 16,555 1907 ~ 16,849 1908 ~ 17,103 1909 ~ 17,272   1910 ~ 17,596 1911 ~ 17,880 1912 ~ 18,190 1913 ~ 18,395 1914 ~ 18,601 1915 ~ 18,808 1916 ~ 18,996 1917 ~ 19,193 1918 ~ 19,460 1919 ~ 19,521 1920 ~ 19,683 1921 ~ 19,831 1922 ~ 20,021 1923 ~ 20,160 1924 ~ 20,296 1925 ~ 20,470 1926 ~ 20,664 1927 ~ 20,845 1928 ~ 21,177 1929 ~ 21,352   1930 ~ 21,470 1931 ~ 21,724 1932 ~ 21,855 1933 ~ 21,950 1934 ~ 21,987 1935 ~ 22,100 1936 ~ 22,280 1937 ~ 22,360 1938 ~ 22,575 1939 ~ 22,650 1940 ~ 22,850 1941 ~ 22,950 1942 ~ 23,140 1944 ~ 23,164 1945 ~ 23,177 1946 ~ 23,204 1947 ~ 23,238 1948 ~ 23,250 1949 ~ 23,274 1950 ~ 23,310   Tiffany & Company ~ A Brief History The Tiffany dynasty was founded in 1837 at 259 Broadway in New York City by Charles Louis Tiffany and partner John B. Young. It began not as a jewelry & silver emporium, but as a purveyor of stationery and fancy goods under the name Tiffany & Young. Although America was in a deep economic recession, the store soon acquired a respected name and flourished with its quality merchandise imported from Europe, India and the Orient. In 1841, a new partner, J. L. Ellis joined the firm and the name changed to Tiffany, Young & Ellis. The first of the Tiffany 'Blue Book' catalogs appeared in 1845 and with it the first indications of silver merchandise carried; a small range of personal items and all, almost certainly, imported. The firm expanded to larger quarters at 271 Broadway in 1847, the move enabled a significant increase in the retailing of silver and jewelry. It is here that American made silver finally took its place alongside the Tiffany name. The goods were made mostly by New York City silversmiths and often bore their maker's marks, as well as the Tiffany retailer's mark. 1851 was an important year in the history of American silver, Tiffany, Young & Ellis, seeking to give their silver goods distinction, became the first American firm to introduce the use of the English Sterling (.925) standard in American made silver. Deciding that they wanted more control, they contracted with the firm of John C. Moore, one the finest American holloware silversmithies, to produce exclusively for Tiffany's. Both Young & Ellis retired in 1853, giving Charles Tiffany control of the firm, again he moved it to larger quarters at 550 Broadway and the name was changed to that which we know today, Tiffany & Company. Over the next two decades, Tiffany worked closely with J. C. Moore and, increasingly with his son, Edward Chandler Moore, who had fully taken the reins of Moore concern in the 1860's. Together, the artist Moore and the businessman Tiffany, created many landmark pieces of American silver and spread the fame of Tiffany & Company silverware. In 1867, at the Exposition Universelle in Paris, Tiffany's became the first American firm to win an award for excellence in silver. Charles L. Tiffany made a landmark decision in 1868, he reached an agreement with Edward C. Moore and purchased the Moore firm. At this juncture, Tiffany & Company became a silver manufacturer as well as a silver retailer. For his part, Edward Moore became a Tiffany stockholder and the general manager of the silverware end of the business. His first important step was to expand production to include flatware manufacturing. In 1869 "Tiffany", the company's first flatware pattern, premiered and the firm moved to new and larger quarters on Union Square. Moore was a cultured man, an avid world traveler and collector of art and objects of the Near & Far East. As the Aesthetic Movement style became fashionable, his innovative nature and knowledge of Eastern art combined with his superlative design skills to bring Tiffany's to the forefront of American silver manufacturers. Many of the finest Japanesque and Moorish Revival objects ever created, including major presentation pieces, were made by Tiffany & Company at this time. By the time of Edward Moore's death in 1891, Tiffany & Co. had won major awards at successive European and American Expositions and had become the most internationally respected American silver manufacturer. The founder, Charles L. Tiffany passed on in 1902, leaving a legacy based on sound business judgement and goods of exceptional quality. Tiffany & Company moved to its present quarters at 5th Avenue & 57th Street in 1940 and remained in the hands of the Tiffany & Moore families until 1955. this article is based on a page available in www.925-1000.com website upon kind permission of Tom Guarrera - ASCAS member   a selection of Tiffany silver pitcher 922 6677 coffee pot 10166 2266 pitcher 3077 M 7306 tazza 22796 dresser/vanity set 15088G 14562 teapot 6393 M 7700 cream and sugar 2551 M basket 1383 3 T 1049 tea set 1318 1581 basket 16942 bowl 12445 T 555 compote 19754 6618 pill box * 174 MI maker: Argenteria Galbiati srl Milano Italy coffee set 20999 7856   plate 11085 7435 urn vase 11251 T 4374 asparagus tongs 1622 pitcher by Elsa Peretti - Italy