The current market for Islamic art may not be as hearty as Sotheby's had hoped.

Both an evening sale in London on Tuesday and a day sale there this afternoon finished short of expectations, with more than half the lots bought in. The auction Tuesday night was expected to realize £9-13 million ($14-20 million), but barely eked out £3 million ($4.7 million), with a dismal 30 percent of lots finding buyers. The day sale today did only slightly better, with £5.5 million hammered down (£9 million was the pre-sale estimate), and 160 of 363 lots finding buyers, for a 44 percent sell-through rate.

Over half of the items featured at Tuesday's evening auction were property from the collection of Harvey B. Plotnick, a Chicago collector who bought his first piece of Islamic art on a whim in Paris in the early '90s and, in the years since, has assembled one of the world's largest collections of medieval Islamic pottery. Most of the works offered were also included in the Art Institute of Chicago's 2007 show "Perpetual Glory: Medieval Islamic Ceramics from the Harvey B. Plotnick Collection."

The pottery that Plotnick consigned to Sotheby's is originally from medieval Persia, Iraq (the cultural center of the Islamic world during the Abbasid Caliphate, from the 8th to the 13th centuries), and central Asia. An Abbasid pottery bowl with a Kufic inscription (est. £150,000-200,000, or $230,000-310,000) from 9th-century Iraq was bought in. However, a rare Abbasid lustre bowl from the same period did sell for just over £300,000 ($470,000), squarely within its £250,000-350,000 ($390,000-545,000) estimate.

A silver-inlaid brass ewer dating from 13th-century Khurasan in central Asia carried Tuesday evening's highest estimate (£2-3 million or $3.1-4.7 million). It also went unsold. 

One ray of light in the gloomy results was the performance of historic items of clothing. The medieval Islamic equivalents of haute couture fared well. A post-Sasanian (7th-9th century) silk shirt from central Asia, woven with cream, honey, and blue silk and decorated with a pheasant pattern that connoted regal stature, sold for £713,250 Tuesday evening, well above the £600,000 ($930,000) low estimate. This afternoon, a silk tunic dating from the 8th century in central Asia, estimated between £400,000 ($620,000) and £600,000 ($930,000), fetched £480,000 ($750,000).