Double diamond

Double diamond may refer to:

Singing

Singing is the act of producing musical sounds with the voice, and augments regular speech by the use of tonality, rhythm, the use of sustained tones and a variety of vocal techniques. A person who sings is called a singer or vocalist. Singers perform music (arias, recitatives, songs, etc.) that can be sung without accompaniment or with accompaniment by musical instruments. Singing is often done in a group of other musicians, such as in a choir of singers with different voice ranges, or in an ensemble with instrumentalists, such as a rock group or baroque ensemble. Singers may also perform as soloist with accompaniment from a piano (as in art song and in some jazz styles) or with a symphony orchestra or big band. There are a range of different singing styles, including art music styles such as opera and Chinese opera, religious music styles such as Gospel, traditional music styles, world music, jazz, blues and popular music styles such as pop and rock.

Singing can be formal or informal, arranged or improvised. It may be done for religious devotion, as a hobby, as a source of pleasure, comfort, or ritual, as part of music education, or as a profession. Excellence in singing requires time, dedication, instruction, and regular practice. If practice is done on a regular basis then the sounds can become more clear and strong. Professional singers usually build their careers around one specific musical genre, such as classical or rock, although there are singers with crossover success (singing in more than one genre). They typically take voice training provided by voice teachers or vocal coaches throughout their careers.

Diamond

In mineralogy, diamond (/ˈdaɪəmənd/ or /ˈdaɪmənd/; from the ancient Greek ἀδάμας – adámas "unbreakable") is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the strong covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material. Those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells.

Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron and nitrogen. Small amounts of defects or impurities (about one per million of lattice atoms) color diamond blue (boron), yellow (nitrogen), brown (lattice defects), green (radiation exposure), purple, pink, orange or red. Diamond also has relatively high optical dispersion (ability to disperse light of different colors).