If a decanter is lead crystal, there should be a mark on the bottom of the item. You can read more about lead crystal at http://www.wisegeek.com/what-is-lead-crystal.htm.
I can't tell if you mean "crystal" as in "made of a crystalline material" or "crystal" as in "made of lead crystal, which is not technically a crystal at all". Take it to a jeweler. There's not any simple foolproof way a layman could tell.
I assume you mean pure Lead, and I'm here to tell you that Lead is an element in the periodic table. The fact that it is an element means that it is only 1 type of atom; Lead! The atomic symbol for Lead is Pb.
You can tell a hydrated crystal is dry by conducting a weight measurement before and after drying. A decrease in weight indicates that water has been removed. Additionally, the crystal may appear opaque or have a different color when hydrated, which can change back to its original appearance when dry.
The shape of a crystal is determined by the arrangement of atoms and molecules within the crystal lattice. Different crystal structures exhibit unique geometric shapes due to the repeating pattern of atomic arrangement. By studying the external geometry of a crystal, scientists can infer information about its internal atomic structure, such as bond angles, symmetry elements, and unit cell dimensions.
XRD (X-ray diffraction) is a technique used to analyze the crystallographic structure of materials. It provides information on the crystal structure, phase composition, and crystallite size of a sample, helping to identify the different phases present in the material and their arrangement in the crystal lattice.
Crystal and glass are the same thing. Crystal is glass that contains lead. When lightly tapped it has a sharp ring compared to plain glass.
The best way to find out how much your antique crystal decanter set is worth, is by taking it to your nearest local antique dealer. They should be able to tell you how much it is worth and other information about the set.
You Really can't
I can't tell if you mean "crystal" as in "made of a crystalline material" or "crystal" as in "made of lead crystal, which is not technically a crystal at all". Take it to a jeweler. There's not any simple foolproof way a layman could tell.
I can tell you 1575 is only the date Bols (Made liquor) was founded. not when the decanter was made. Delft is the company who made the decanter and they are stilll in business as Royal Delft.
Take your crystal to a local jeweler who can use a probe to help you determine whether or not your crystal is a diamond.
Easly
Most of the time it will. Good crystal always will. You can tell crystal from glass by lightly tapping the side of the glass, vase, or item. When you do this you will get a ringing sound from crystal and a "thump" sound from glass.
Radioactive isotope analysis &/or other measurements & calculations on the crystal itself or on its source formation.
Crystal balls are just a transparent sphere. Usually they are made out of glass or crystal. Some legends and myths say that crystal balls are used by fortune tellers to tell the future.
I the crystal is shaped like a banana then it's ions of the internal structure are shaped like an apple. And vise versa.
Its see through and sparkles??????