Segment Information (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Summary of revenue by product type
Revenue	$ 8,307	$ 10,207
Core [Member]
Summary of revenue by product type
Revenue	987	2,758
Polished [Member]
Summary of revenue by product type
Revenue	6,057	5,681
Optical [Member]
Summary of revenue by product type
Revenue	1,144	1,759
Other [Member]
Summary of revenue by product type
Revenue	$ 119	$ 9

Aggregate revenue during the period from the sale of goods in the normal course of business, after deducting returns, allowances and discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(a))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

Name:	us-gaap_SalesRevenueGoodsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration