Abstract: Means are described for suppressing spontaneous diamond nucleation in the vicinity of diamond seed material located in reaction vessel construction used in the growth of diamond by the process disclosed in U.S. Pat. No. 3,297,407--Wentorf, Jr.In assembly of the reaction vessel a portion of the lower surface of the plug of catalyst-solvent metal is disposed in contact with the diamond seed material. Preferably all of the balance of the lower surface area of the catalyst-solvent plug adjacent the seed material is covered with a disc or layer of a material different from the catalyst-solvent metal employed and selected from a list of specific materials that suppress diamond nucleation.

Abstract: Reaction vessel construction is described for suppressing spontaneous diamond nucleation and simultaneously reducing the flaw content in the main body of diamond grown from diamond seed material by the process broadly disclosed in U.S. Pat. No. 3,297,407 to Wentorf, Jr.In the reaction vessel construction the body of catalyst-solvent metal is formed with at least one small tip projecting from the underside thereof. A single diamond seed is placed in contact with this (or each) tip. The underside of the plug of catalyst-solvent metal is in contact with a nucleation-suppressing disc, or layer, of a material different from the catalyst-solvent and selected from a specific group of materials. In each case the tip of catalyst-solvent metal projects through a hole in the disc or layer to make contact with the diamond seed material.

Abstract: Diamond crystals of controlled impurity content and/or impurity distribution and reaction vessel configurations for the production thereof are described. Combinations of "dopant", "getter" and "compensator" materials are employed to produce gem stones of unusual color patterns, or zoned coloration, using specific reaction vessel configurations.

Abstract: Type Ib synthetic diamond crystal is annealed at an annealing temperature ranging from about 1500.degree. C. to about 2200.degree. C. under a pressure which prevents significant graphitization of the diamond during the annealing to convert at least about 20% of the total amount of type Ib nitrogen present in the crystal to type Ia nitrogen.

Abstract: Type Ib or mixed type Ib-Ia natural diamond crystal is annealed at an annealing temperature ranging from about 1500.degree. C to about 2200.degree. C under a pressure which prevents significant graphitization of the diamond during the annealing to convert at least 20% of the total amount of type Ib nitrogen present in the crystal to type Ia nitrogen.

Abstract: Diamond crystals of controlled impurity content and/or impurity distribution and reaction vessel configurations for the production thereof are described. Combinations of "dopant", "getter" and "compensator" materials are employed to produce gem stones of unusual color patterns, or zoned coloration, using specific reaction vessel configurations.

Abstract: Improvements are provided in reaction vessel construction used in the growth of diamond by the process disclosed in U.S. Pat. No. 3,297,407 -- Wentorf, Jr. In assembly of the reaction vessel of this invention, the plug of catalyst-solvent material is disposed between the source of carbon and the diamond seed material as in the Wentorf, Jr. patent and, in addition, the diamond seed material is separated from the catalyst-solvent plug by means for isolating the diamond seed material from the catalyst-solvent material until after the latter has become saturated with carbon from the source of carbon. In addition, preferably the under surface of the plug of catalyst-solvent metal is covered with means for suppressing diamond nucleation. The nucleation suppressing means is usually in the form of a disc and may completely cover the underside of the catalyst-solvent plug or may have a hole therethrough in juxtaposition to the diamond seed/isolating means combination(s).

Abstract: Diamond crystals of controlled impurity content and/or impurity distribution and reaction vessel configurations for the production thereof are described. Combinations of "dopant," "getter" and "compensator" materials are employed to produce gem stones of unusual color patterns, or zoned coloration, using specific reaction vessel configurations.

Abstract: Improvements are provided in reaction vessel construction used in the growth of diamond by the process disclosed in U.S. Pat. No. 3,297,407 -- Wentorf, Jr. In assembly of the reaction vessel of this invention, the plug of catalyst-solvent material is disposed between the source of carbon and the diamond seed material as in the Wentorf, Jr. patent and, in addition, the diamond seed material is separated from the catalyst-solvent plug by means for isolating the diamond seed material from the catalyst-solvent material until after the latter has become saturated with carbon from the source of carbon. In addition, preferably the under surface of the plug of catalyst-solvent metal is covered with means for suppressing diamond nucleation. The nucleation suppressing means is usually in the form of a disc and may completely cover the underside of the catalyst-solvent plug or may have a hole therethrough in juxtaposition to the diamond seed/isolating means combination(s).