US4039726A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Altering the appearance of corundum crystals
Assignee: Astrid Corp Ltd
•
Filing: 1976-03-08
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Granted: 1977-08-02
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Expires: 1996-03-08
Abstract
Abstract The appearance of a corundum crystal is altered by subjecting the crystal to an elevated temperature while maintaining the crystal in contact with a powder comprising a major amount of alumina and a minor amount of a metal oxide colorant.
Inventors
- 👤 Ronald Ray Carr
- 👤 Stephen Dale Nisevich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:08
CPC Classifications
C; C30; C30B; C30B29/00; C30B29/10; C30B29/16; C30B29/22; C30B29/26; A; A44; A44C; A44C17/00; C30B29/20; C30B31/00; C30B31/02; Y; Y10; Y10T; Y10T428/00; Y10T428/31; Y10T428/8305
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
70 words
A corundum crystal initially having a non-uniform color and a surface altered by contact with a powder consisting essentially of alumina and at least one metal oxide colorant at an elevated temperature within the range of 1600° C. to a temperature below the fusion temperature of the said powder, said metal oxide colorant imparting to the surface of the crystal a uniform color appearance without effecting asterism of said crystal.
Claim 2
Dependent Claim
70 words
A corundum crystal initially having a non-uniform color and a surface altered by contact with a powder consisting essentially of alumina and at least one metal oxide colorant at an elevated temperature within the range of 1600° C. to a temperature below the fusion temperature of the said powder, said metal oxide colorant imparting to the surface of the crystal a uniform color appearance without effecting asterism of said crystal.
Claim 3
Dependent Claim
13 words
The corundum crystal of claim 1 wherein said crystal is an asteriated crystal.
Claim 4
Dependent Claim
88 words
A corundum crystal initially having a first color appearance and a surface altered by contact with a powder consisting essentially of alumina and of metal oxide colorant at an elevated temperature within the range of 1600° C to a temperature below the fusion temperature of the said powder, said metal oxide colorant consisting essentially of an oxide of titanium and at least one further metal oxide, said further metal oxide colorant imparting to the surface of the crystal a second color appearance different from the first color appearance.
Claim 5
Dependent Claim
88 words
A corundum crystal initially having a first color appearance and a surface altered by contact with a powder consisting essentially of alumina and of metal oxide colorant at an elevated temperature within the range of 1600° C to a temperature below the fusion temperature of the said powder, said metal oxide colorant consisting essentially of an oxide of titanium and at least one further metal oxide, said further metal oxide colorant imparting to the surface of the crystal a second color appearance different from the first color appearance.
Claim 6
Dependent Claim
14 words
The corundum crystal of claim 3 wherein said crystal is an asteriated crystal. C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-01 | 1981-01-31 | 1981-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-01 | 1985-01-31 | 1985-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-01 | 1989-01-31 | 1989-08-02 | $7700.00 | Window Closed / Lapsed |