A glass having from greater than or equal to about 0.1 mol. % to less than or equal to about 20 mol. % Ho.sub.2O.sub.3, and one or more chromophores selected from V, Cr, Mn, Fe, Co, Ni, Se, Pr, Nd, Er, Yb, and combinations thereof. The amount of Ho.sub.2O.sub.3 (mol. %) is greater than or equal to 0.7 (CeO.sub.2 (mol. %)+Pr.sub.2O.sub.3 (mol. %)+Er.sub.2O.sub.3 (mol. %)). The glass can include one or more fluorescent ions selected from Cu, Sn, Ce, Eu, Tb, Tm, and combinations thereof in addition to, or in place of the chromophores. The glass can also include multiple fluorescent ions.

A glass having from greater than or equal to about 0.1 mol. % to less than or equal to about 20 mol. % Ho.sub.2O.sub.3, and one or more chromophores selected from V, Cr, Mn, Fe, Co, Ni, Se, Pr, Nd, Er, Yb, and combinations thereof. The amount of Ho.sub.2O.sub.3 (mol. %) is greater than or equal to 0.7(CeO.sub.2 (mol. %)+Pr.sub.2O.sub.3 (mol. %)+Er.sub.2O.sub.3 (mol. %)). The glass can include one or more fluorescent ions selected from Cu, Sn, Ce, Eu, Tb, Tm, and combinations thereof in addition to, or in place of the chromophores. The glass can also include multiple fluorescent ions.

A exemplary light emitting device includes an excitation source operable to generate excitation light with a dominant wavelength in a range 450 nm to 470 nm; a red photoluminescence material which generates light with a peak emission wavelength in a range 600 nm to 620 nm with a full width at half maximum emission intensity greater than 70 nm and less than 80 nm; a yellow to green photoluminescence material which generates light with a peak emission wavelength in a range 530 nm to 550 nm; and a narrow-band red photoluminescence material which generates light with a peak emission wavelength in a range 625 nm to 635 nm with a full width at half maximum emission intensity greater than about 5 nm and less than about 25 nm.

The invention relates to a method for the preparation of a lithium silicate glass or a lithium silicate glass ceramic which comprise cerium ions and are suitable in particular for the preparation of dental restorations, the fluorescence properties of which largely correspond to those of natural teeth. The invention also relates to a lithium silicate glass and a lithium silicate glass ceramic which can be obtained using the method according to the invention, the use thereof as dental material and in particular for the preparation of dental restorations, as well as a glass-forming composition which is suitable for use in the method according to the invention.

A glass having from greater than or equal to about 0.1 mol. % to less than or equal to about 20 mol. % Ho.sub.2O.sub.3, and one or more chromophores selected from V, Cr, Mn, Fe, Co, Ni, Se, Pr, Nd, Er, Yb, and combinations thereof. The amount of Ho.sub.2O.sub.3 (mol. %) is greater than or equal to 0.7 (CeO.sub.2 (mol. %)+Pr.sub.2O.sub.3 (mol. %)+Er.sub.2O.sub.3 (mol. %)). The glass can include one or more fluorescent ions selected from Cu, Sn, Ce, Eu, Tb, Tm, and combinations thereof in addition to, or in place of the chromophores. The glass can also include multiple fluorescent ions.

A glass having from greater than or equal to about 0.1 mol. % to less than or equal to about 20 mol. % Ho.sub.2O.sub.3, and one or more chromophores selected from V, Cr, Mn, Fe, Co, Ni, Se, Pr, Nd, Er, Yb, and combinations thereof. The amount of Ho.sub.2O.sub.3 (mol. %) is greater than or equal to 0.7 (CeO.sub.2 (mol. %)+Pr.sub.2O.sub.3 (mol. %)+Er.sub.2O.sub.3 (mol. %)). The glass can include one or more fluorescent ions selected from Cu, Sn, Ce, Eu, Tb, Tm, and combinations thereof in addition to, or in place of the chromophores. The glass can also include multiple fluorescent ions.

A exemplary light emitting device includes an excitation source operable to generate excitation light with a dominant wavelength in a range 450 nm to 470 nm; a red photoluminescence material which generates light with a peak emission wavelength in a range 600 nm to 620 nm with a full width at half maximum emission intensity greater than 70 nm and less than 80 nm; a yellow to green photoluminescence material which generates light with a peak emission wavelength in a range 530 nm to 550 nm; and a narrow-band red photoluminescence material which generates light with a peak emission wavelength in a range 625 nm to 635 nm with a full width at half maximum emission intensity greater than about 5 nm and less than about 25 nm.

The invention relates to faceted gemstones based on a luminescent glass composition that contains particular oxides of rare earth metals and thus enables the faceted gemstones to be identified, and to a process for identifying the gemstones.

The invention relates to a method for the preparation of a lithium silicate glass or a lithium silicate glass ceramic which comprise cerium ions and are suitable in particular for the preparation of dental restorations, the fluorescence properties of which largely correspond to those of natural teeth.

The invention also relates to a lithium silicate glass and a lithium silicate glass ceramic which can be obtained using the method according to the invention, the use thereof as dental material and in particular for the preparation of dental restorations, as well as a glass-forming composition which is suitable for use in the method according to the invention.

The invention relates to a method for the preparation of a lithium silicate glass or a lithium silicate glass ceramic which comprise cerium ions and are suitable in particular for the preparation of dental restorations, the fluorescence properties of which largely correspond to those of natural teeth. The invention also relates to a lithium silicate glass and a lithium silicate glass ceramic which can be obtained using the method according to the invention, the use thereof as dental material and in particular for the preparation of dental restorations, as well as a glass-forming composition which is suitable for use in the method according to the invention.